Historically I often wondered if the 124A did a U turn at the Bexley Hospital terminus, or if it continued up to the roundabout above the A2 to turn round. I was very young then and as it only operated Sunday Afternoons , never saw it to find found !
I also remember the route existing but never travelled on it.
Old OS maps suggest there was enough room to do a U-turn (from the west for the 124A and from the east for country bus routes) in front of the gate house. 1983 photo on Flickr (not my photo / account)
here
Historically, there was a u-turn on Bishopsgate for buses terminating at Liverpool Street Station from the north (following trolleybus practice) - think this was still happening in to the 1980s (regularly on route 149 and possibly as a short working on other routes.)
The 277 / 279 terminus at Smithfield (St John Street) was a fairly tight turn, but not quite sure if it qualifies as a U-turn, it was round a 'gents' on an island in the middle of the road (the island is still there, the 'gents' isn't.)
I have also seen a photograph of the 'inter station' night bus doing a U-turn leaving the eastbound Euston Road / Kings Cross Station stop to go towards Euston - this must have been before there was a central barrier, and probably wasn't the official working.
The North Woolwich terminus for route 101 and trolleybus / trolleybus replacement routes probably also counted as a U-turn until the roadway / bus stand north of the pedestrian tunnel entrance was opened. 1970 photo (also on Flickr, not mine or my account)
here.
I also have an idea that in the early years of the south London tram replacement routes, the Victoria (Vauxhall Bridge Road) terminus was initially a u-turn, northbound to southbound, before the loop via Wilton Road started.
