Very definitely after the fact ....
Given that boro has just done a loft conversion - I guess there might not be many rafters that a poke through the roof job would easily answer.
But I would like to throw-in a daft one. What goes up a wall to the roof. A chimney? And where is boros install?
Being the daft self-installer that I am (i.e., absolutely my own stuff, lol) - I would think chimney breast/party wall. So, a lenghty pole, flashed on the roof, but, anchored firmly on the inside attic wall: thus, not requiring any chimney attachments.
The neighbourhing houses give you some idea of their 'age' - and that chimney does look like it needs some attention: with or without the fantastic new sat kit.
I say, good on boro for pulling-off a self-install - even though I know the pros here have the experience to pull the chimney down with their knowledge, lol.