This too rings a bell and i'm trying to place it ... yes.. got it! ... ... No ... it's gone again ... .. somewhere in ... ... ... London? ... Yes!!! ... oh! but you've already said that ... ... Now that might be a Hawksmoor church ... ...
...btw, lots of fences in your excellent bus window shot; may I borrow it for an HFF!

Bollards! It's James Gibbs!
But I won't take offence if you want to use it for your HFF.
Taken on a Wednesday, actually.

Ghosts of Christmas Past in Trafalgar Square:
www.youtube.com/watch?v=gPjV5BzJPSY

Sixties snowball fight:
www.youtube.com/watch?v=q5Zac0Tl8II

Bigger fountains and plenty of pigeons:
www.youtube.com/watch?v=kRQTOAKKrpo

1955:
www.youtube.com/watch?v=DKsZiWIeYfc

1968:
www.youtube.com/watch?v=at2tmgCDnQM

And more pigeons:
www.youtube.com/watch?v=t2_V73suh1Q