I saw two more handcycles in RP that evening - this time on the road crossing the park from Robin Hood Gate to Ham Gate.
This morning, I saw a Specialized StreetStomper - evidently a hybrid model, trading on the success of the StumpJumper and RockHopper. Pretty rare, I think, though not desperately exciting of itself. What
was interesting was the horizontal dropouts, part of which was blanked off in the drive side only. I've never seen this before, and can't think what the purpose might have been.
In Streatham, I also saw a Dave Quinn, which I was surprised had not been turned into a fixed, but was still running 12-speed (I think).