had a similar experience in surbiton, surrey a couple of years ago whilst on the way to work 9am on a Sunday morning
came up to a "T" junction to turn right, slowed down and was suddenly thrown over the bars into the main road. thank god no traffic was coming
left bloodied and bruised (ripped shorts and jersey), and bike had damage (bent front wheel, ripped saddle, ripped bar tape, etc.)
managed to recover my wits and inspected the road. Found a deep "trough" in the tarmac where buses had been braking for the junction. When I say deep it was approx 5" deep, about 4" across and 4 feet long. Very hard to see as there was a road marking in front of this trough which being tarmac blended with the road
went back with a friend, took a camera and tape measure to photograph to scale this defect. Also took photos of all injuries, damage to bike and visited GP for check up.
At the time I was an experienced (former professional) freeride mountain biker and also road cyclist, so not a usual "user error"
contacted the local council, who denied all responsibility.
took it up with a local cycle club who had complained to the same council on a number of occasions about this "defect"; they put me onto a "no win, no fee" accident claims company.
they were given the run around by the council for 6 months with no result, as the council claimed they had "lost" any records of the cycle club's complaints, someone vaguely remembered the complaints (phone calls and posted letters) but no written records could be found.