It is November, and bitterly cold even at noon.

This, and the mention of parkland presumably ruling out Antarctica, indicates that the story happens in the northern hemisphere.

at noon. (…)
(…) the single door to the Folly (…)
the sun shining directly through the open doorway.

So the only door of the Folly is to the south.

moving northwards across virgin snow towards the mansion.

The door of the Folly is on the side opposite to the direction of the mansion.

Looking back, you see a maid, Avigrail, running out of the Folly in a terrible state.

So I'm already around the side of the Folly opposite to the sole door, yet I can see the maid running out? And then the gardener comes around too. Hmmm.

then they both go running to the mansion to raise the alarm.

And yet they don't encounter me. Nor do they notice the prints that I just left walking “across virgin snow towards the mansion”.

But enough lollylagging! None of this is terribly relevant…

You leave the Folly, moving northwards across virgin snow towards the mansion.

So I just discovered a murder, and I don't go and report it straight away: the gardener and the maid know the grounds well and thus presumably took the most direct route to the mansion — the same route I took on the way there. I, on the other hand, sneaked around the footmen and hid in the snow (amongst the ice sculptures?), so that I somehow managed to not be noticed by either the maid or the gardener. Why am I so keen not to make my presence known?

I am either the murderer or an accomplice. We don't have enough information to know who the accomplice might be — I consider everyone on the estate suspect.

Oh, and given how cold it is, the icicle wouldn't have melt. Did I by any chance chuck it into the fireplace while you were in the mansion? I hope someone took note if any fire had been recently doused.

Well, except that I know I didn't do all of this. This story is bogus — I was indeed framed. The narrator is therefore the one who's lying to cover up for the murder he committed or was an accomplice in.

It is November, and bitterly cold even at noon.

This, and the mention of parkland presumably ruling out Antarctica, indicates that the story happens in the northern hemisphere.

at noon. (…)
(…) the single door to the Folly (…)
the sun shining directly through the open doorway.

So the only door of the Folly is to the south.

moving northwards across virgin snow towards the mansion.

The door of the Folly is on the side opposite to the direction of the mansion.

Looking back, you see a maid, Avigrail, running out of the Folly in a terrible state.

So I'm already around the side of the Folly opposite to the sole door, yet I can see the maid running out? And then the gardener comes around too. Hmmm.

then they both go running to the mansion to raise the alarm.

And yet they don't encounter me. Nor do they notice the prints that I just left walking “across virgin snow towards the mansion”.

But enough lollylagging! None of this is terribly relevant…

You leave the Folly, moving northwards across virgin snow towards the mansion.

So I just discovered a murder, and I don't go and report it straight away: the gardener and the maid know the grounds well and thus presumably took the most direct route to the mansion — the same route I took on the way there. I, on the other hand, sneaked around the footmen and hid in the snow (amongst the ice sculptures?), so that I somehow managed to not be noticed by either the maid or the gardener. Why am I so keen not to make my presence known?

I am either the murderer or an accomplice. We don't have enough information to know who the accomplice might be — I consider everyone on the estate suspect.

Oh, and given how cold it is, the icicle wouldn't have melt. Did I by any chance chuck it into the fireplace while you were in the mansion? I hope someone took note if any fire had been recently doused.

Well, except that I know I didn't do all of this. This story is bogus — I was indeed framed. The narrator is therefore the one who's lying to cover up for the murder he committed or was an accomplice in.