The ride was going well, a mild and dry night, when I had a puncture just outside of Basildon. That was almost sorted, but when I was tightening up the Allen key style quick release skewer, it sheared off. Aperitif managed to unscrew the end, and reversed, it was just enough to tighten the axle in the drops.
I decided that out would have been too risky to try and continue like that, so I'm currently sat on Laindon Station, waiting for a train back to London, after very gingerly cycling a couple of miles. It did make one horrible graunching sound, so I think this was the right decision.
Rather annoyingly, this is the first FNRttC which I haven't completed, in seven years!