Wrap-up: The Making Of Only time will tell
This is not a solution to the puzzle, but provides notes from its poser. This type of answer has been approved by the community.
Caution: This post may contain spoilers.
(I am awarding the checkmark to @fljx for finding the codename of the mission; however, I'd like to present a walkthrough of the full intended discovery path, highlight the full use of Google Maps during the solution, and round off the story with some remarks relating to the narrative...)
Inspiration
With this month's Topic Challenge being on the subject 'Time', I wanted to create a puzzle involving hidden days of the week, a little like how I had previously done with months of the year in Can I have a 'P' please, Bob? Being a sucker for a geography puzzle, I ideally wanted to find place names that contained the short 3-letter abbreviations for days of the week in English (Mon, Tue, Wed, Thu, Fri, Sat, and Sun), which was something I got close to doing previously with A week around Europe but had ended up settling for days of the week in different languages...
Creative/Logistical steps (including intended solution path)
1. Searching for suitable locations
Initially, I tried to find countries of the world whose names contained these substrings, but struggled with TUE, SAT and SUN (MON was prevalent - MONgolia/MONtenegro/MONaco/soloMONislands - and FRI appeared in any country name with aFRIca within it, while sWEDen and liTHUania did the job for the other two...). So I turned my attention to Google Maps and noted that - for me, at least, being based in the UK - by typing these strings into its search bar it often came up with useful suggestions within my own country: MONmouth, TUEbrook, WEDnesbury... In fact, it was only really with 'SAT' that Google Maps struggled. However, by searching for lists of UK towns and villages online, I was able to Ctrl+F my way through them to find candidates containing this substring.
1b. Thinking up a useful connection
At this point, I didn't have a puzzle - just a list of places with a shared theme. But what else exactly could link Tuebrook (a relatively obscure suburb of Liverpool) with Thurleigh (a village in Bedfordshire) and Sunderland (a major UK city)? It was when searching for 'Wednesbury' in Google Maps that an answer presented itself - the image stub for the town contains a clock tower!

So was born one of my usual 'I wonder if...' ideas - namely, I wonder if I can find clocks in each of these places on Google Maps?
I substituted MONument for MONmouth, as there was a very nice clock on a building just above the Monument tube station in London that I'd spotted when considering whether I could find seven London tube stations that would work:

TUEbrook had the potential to make or break the puzzle, as very few UK high streets contain prominent clocks. So I was absolutely delighted while trawling Street View on its roads to stumble upon one on the corner of Snaefell Avenue, above what is now an off-licence but was once a bank - a far more likely institution to have a clock on its front!

WEDnesbury's clock was, of course, already established...

And then came the hunt for another type of building that often comes with a clock built in - churches! These came with the added bonus of being marked on the aerial views, so I could focus my attention on these pretty efficiently without having to trawl the streets excessively. I found one in THUrleigh, just about visible from the road...

...then another in FRImley, albeit viewable only on an angle rather than head-on:

Meanwhile, a search for 'Sunderland clock tower' immediately brought up an array of articles and images about various clocks that could be seen around the town, so I was spoiled for choice, eventually opting for a prominent one in the city centre:

This just left me with 'SAT' to find, and try as I might I just could not find anything suitable in Satley, Satmar, Satron, Satterleigh, Satterthwaite or Satwell, which were all suggested on a list of UK 'S' placenames. Instead, I had to concede that perhaps I needed a place that didn't necessarily begin with 'SAT' but contained it somewhere else within its name. Eventually - by examining the lists for other letters of the alphabet - I stumbled upon 'Thorpe SATchville'. I headed straight for the church on Street View... but it wasn't visible from the road. So I trawled the village streets instead, hoping I might find something... and then, atop practically the last house in the village, I spotted this:

Words cannot describe how happy this discovery made me - everything had fallen into place!
2. Finding ways to clue the locations
So I had a collection of clocks that naturally presented a 'Find the place from the clock' type of puzzle. However, more clues were going to be needed as none were especially well-known (these weren't exactly Elizabeth Tower or the Liver Building, after all), and attempts to reverse image-search them were largely unsuccessful (which made me happy - I was going to need to be creative to lead solvers to the answers). What naturally presented itself to me was maps.
Perhaps it would be possible to present some aerial satellite views and get people to identify them just from the images? Yeah, good luck finding Thorpe Satchville, buddy...
Well, how about presenting street maps? That would be too easy to type a few street names into Google and have an answer immediately. While I liked the idea of a Google Maps treasure hunt, that really only merited being a small part of the puzzle, rather than its entirety...
So how about taking some of the street names from the maps and disguising them? e.g. with a substitution cipher or picture rebus clues... Say, four or five for each, to be sure of finding a unique location where all the street names appear in one place (the ubiquitous 'High Street' or 'Church Road' on its own would be pretty useless...). I liked this idea... but how to make sure all the selected street names played their part? (Since it would be possible in some cases to pinpoint a map based on just one or two very rare names...)
This was when it struck me that if I employed a different method of disguise for each map's street names, I could distribute the whole lot of them out of order, all mixed together, and present their disentanglement and grouping as a key part of the puzzle. Much like a connect-wall in fact...
3. Disguising the street names
After considering many approaches that either were too basic (substitution ciphers like A1Z26, rot-13...) or just did not work (trying to find street names that could be made entirely from Periodic Table symbols...) I settled upon seven that felt deserving of their place in the puzzle.
Crucially, I wanted all disguises to use only strings of letters - no numbers, no pictures, no special characters, as these would lead to immediate obvious groupings. What I really wanted was for a solver to pore over the list, trying to spot commonalities between certain clue structures, helping them to match them up and work out what was going on.
In fact, in the final puzzle I presented the seven map images in roughly the order I expected a solver coming in blind to disentangle them. This is the rough thought process I suspected a new solver might end up following:
A. Homophones - perhaps the most obvious street name disguises of the lot.
MA KIT PLAICE = MARKET PLACE (*)
UP A HEIST REET = UPPER HIGH STREET
RID IN GLAIN = RIDDING LANE? (*)
WAR PHHT AILS TREAT = WHARFTAIL STREET?
Searching Google for the two with asterisks yields Wednesbury, from where the others can be confirmed as RIDDING LANE and WHARFEDALE STREET, and SHAM BULLS = SHAMBLES found.
B. Some others look like crossword or quiz clues with answers that can be found online:
ISLE OF MAN MOUNTAIN = SNAEFELL (*)
BC CAPITAL = VICTORIA
CAMERON'S CHANCELLOR = OSBORNE (*)
AQUILO HOMETOWN = SILVERDALE
SECOND ARGONNE DIRECTOR = HILBERRY (*)
Searching Google for the asterisked words yields links to streets in Liverpool. Adding SILVERDALE makes it pretty much definitive. It’s clear from Google Maps that the area is called Tuebrook.
C. There are some which have extra letters:
BACKERS [P]LANE – likely BAKERS? (*)
CHURCH[Y] LAN[C]E – surely CHURCH LANE... (*)
GREAT[S] DEALBY [B]ROAD – just need to work out the middle part...
SALUTER'S [C]HILL DRIVE[L] – first word not sure yet..
TWAYFORD ROA[L]D – a Google search suggests TWYFORD ROAD (*)
Searching for the asterisked answers does potentially lead people to Thorpe Satchville, small as it is...
D. There are now 5 remaining sets comprised of real words = Possible anagrams?
BRUTAL DECREMENTS
HORNET JEST
WET FACT TESTER
DEFTER DEBTORS
BIG BRACKETS DETER
All of these contain the letters of STREET, giving us:
er... CRUMBLED AN STREET (not too far off CUMBERLAND?)
JOHN STREET (no doubt)
hmm... FEW TACT STREET (could eventually get FAWCETT)
BEDFORD STREET (little else it could be)
BACK BRIDGE STREET (without too much fuss?)
Searching the two known ones leads to Sunderland very quickly.
So what of the remaining more nonsensical-looking entries?
E. Several - six, in fact - are missing vowels altogether:
MLL HLL
GLB CLS
PX RV
VCRG GRN
HGH STRT
TH CLS
Among these we have a very recognisable HIGH STREET, MILL HILL and THE CLOSE. On their own these don’t yield much. VICARAGE GREEN is key, which then leads to profitable Google searches turning up hits in the Bedford area, leading ultimately to Thurleigh. This allows us to inspect the map and find GLEBE CLOSE. PX RV must therefore belong to something else.
Let’s look at the remaining ten:
EASTCHP
RV COS OD
ASNG WY
FISH TRE L
HRH OD
PUDING LAE
CANO STRE
PX RV
KING WLAM STRE
RME GEN OD
F. Among these, some seem to contain almost-complete words: EASTCHP, PUDING LAE, CANO STRE, and KING WLAM STRE for four. Two of these appear to be corruptions of some kind for PUDDING LANE (a famous street from history) and KING WILLIAM STREET. Can we find those together on a map? YES! In London, near Monument, where we also clearly see EASTCHEAP, CANNON STREET and can find FISH STREET HILL. All of these are words where only the first occurrences of letters are presented.
G. Among our final five survivors (RV COS OD, ASNG WY, HRH OD, PX RV, RME GEN OD) we see some repeating patterns – notably three contain 'OD' as a word. These are the alternate letters of ROAD; WY is alternately WAY also; RV? Let’s see... If the other words also have alternate letters missing, PARSONAGE WAY is a great candidate (with PARSONAGE findable using a tool like Qat as being the only common word of the form _A_S_N_G_). We may also have spotted the 'days of the week' pattern by now and be looking for a place beginning with FRI, so Frimley comes up... It's conveniently a short side-road that can be precisely placed and we can soon find APEX DRIVE, FRIMLEY GREEN ROAD, CHURCH ROAD and GROVE CROSS ROAD in the same screenshot.
Thus, all seven groups end up solved!
4. Providing a purpose!
While all of this was good fun, what was going to be the end point of the puzzle? A natural mechanism would be to end up needing to extract a substring from the location names. So we would need a way to clue which letters in the words were important and we already had an obvious source of numbers built in to the puzzle - the clocks themselves! What more apt way in a time-themed puzzle could there be?
To find potential words I transcribed the times visible on the clocks in the Street View images and noted down the letters found when indexing into the place names at those points. Attempts to find real seven-letter words or phrases from the place names in weekday-substring order or alphabetical order were unsuccessful, as were attempts to create words by ordering the towns by their longitude or latitude, or the clocks by the time they were showing. In the end I had to opt for an ordered key of Greek letters (which I used to avoid too much confusion with the various other letters and numbers appearing in the puzzle) and a small visual hint (the use of MISSION, or 'MON') to suggest ordering the place names by their weekday substrings before carrying out the extraction.
5. Adding a story
The whole puzzle needed context, a story of some kind to help make sense of it. The notion of using 'MISSION' suggested the front of a file in a secret intelligence setting. But why would the contents of this file be all this??
In the end I hope I laid enough clues in the chosen story to suggest...
...the narrator is renowned for barely listening to things people say, always too busy with their nose in their own work, working on their cases. The file is therefore entirely false, but being used by a desperate colleague who knows this is the only way to get the employee's attention and pass on a message.
What the boss said upon leaving the office on a Friday (the natural end of the working week) was that they were going to take... a holiday, a vacation, some time out. Once the non-listening employee finally gets to the bottom of the fake casefile's mystery, the words 'TIME OUT' are what they discover. This solution and scenario also explains why the employee's other colleagues are completely unconcerned - they all listened to the boss on Friday; they know he's got a few days off and there's nothing to worry about! It's a lesson for the employee to listen more in future... A cautionary tale!
Overall intended solution path summary:
- Use the clues to identify road names following a particular pattern.
- Use the road names, a web browser, and Google Maps to find (i) the relevant aerial shot, (ii) the name of the town/area (in either order).
- Use Google Street View to find which clock is found on each yellow spot.
- Use the time on the clock face, the name of the town, and the answer key to find the hidden word.
- Deduce the relevant story context.
Resources
As mentioned above, the entire puzzle was devised with the help of Google Maps, especially Google Street View, using Microsoft's Snipping Tool app for taking screenshots easily. Images were modified just in Microsoft Word, with yellow circles added to the maps to indicate the locations of the clocks.
A few tips for those wishing to make use of Google Maps in their own puzzles:
- At present, it is not possible to remove street names and labels from the default map view on Google Maps. It is possible in 'Satellite' view, however - once in that mode, simply select 'More' from the other options displayed, then untick the 'Labels' box at the bottom:


- If you don't want Google Maps' default red pin displayed on your screenshot, don't forget to press 'X' by the search bar to clear the current search. The map view will remain the same and you can take your screenshot unobstructed.
Takeaway
As a map lover, I had a lot of fun making this puzzle, and I hope others have enjoyed (or will enjoy) solving it. It was particularly satisfying to be able to include both clocks and days of the week in my contribution to this month's time-themed challenge, and I personally feel the Google Maps treasure hunt is quite a good one, with plenty of clues to help solvers find their way. (You, of course, may have a different opinion, and that's fine!)
How I would have loved the London Underground version to have worked out though... That way you'd have all got to share in the joy discovering this 'happy chappy' standing proudly beneath his clock in BlackFRIars!

Thanks for reading :)
Stiv.