[bombcar]

That's an exceptionally clean tree-felling, though the position of the hinge indicates it was meant to fall toward the wall.

The paint looks like an indication on how big to make the hinge, which actually suggests someone who "knows what they're supposed to be doing" but not "used to doing it all the time".

[RobotToaster]

So potentially, "someone who just watched a youtube video on how to fell a tree"?

[bombcar]

That's what I would suspect. Someone who did enough research but hadn't really done it before.

But! It also looks pretty clean for a "first try" so maybe the paint is something else.

[mytailorisrich]

I have felled a couple of old apple trees in my garden with a chainsaw after watching a "few Youtube videos".

The trunks were maybe 30 to 40cm in diameter so obviously much smaller trees than that sycamore (well apple trees for a start and much younger) and I can tell you that this is one of those things that looks easy when you watch but not so much when you do it. Handling a chainsaw to be able to make clean, straight cut through takes practice and you need a good chainsaw as well.

So IMHO there is no chance in hell that the sycamore was felled by an amateur.

I believe that one has to be at least 16 to become a trainee so maybe that 16 year old has received previous training and/or his family works in the field. Or he didn't do it himself.