It must have been windy out last night, my wheely bin had been blown over (first time ever), and crossing Clapham Common, two trees seem to have gone over, right next to each other, alongside the cycle path. It would be a very odd place for someone to have collided a vehicle with them (although not impossible), so I'm assuming a freak very localised gust took them out.
A couple of years ago, a tree near the traffic lights adjacent to Narbonne Avenue fell across the road, killing the driver of a van, and injuring two passengers, who had to be cut out of the van, but that tree was apparently not in a very healthy condition, according to locals interviewed at the time. The two trees I saw today, looked to have been as healthy as any of the other trees running alongside the paths.