Heads Up for Pied Wagtail Roosts

Anybody in the City Centre as the sun goes down?
It's worth keeping an eye open for those Pied Wagtail roosts. Any tree that's still in leaf will do, preferably under a street light or near a hot air vent.
The last one I saw was in the tree on Market Street by the Woolshops, about 2 or 3 years ago.