A gentle 12km or so last night turned out to be a match for my PB on that route to the second. Must be the new shoes. Still not feeling like running 5 or 6 times a week. I think my natural limit may be a half marathon, and the full one is going to wipe me out for a month or so.
Meanwhile, I re-read the symptoms of over-training in The Book, and listed there is diarrhoea. And guess what..? Maybe that's why I'm losing weight - it's got nothing to do with fitness, it's the dysentery effect. Oh well, every kilo is another one I don't have to lug around the streets of London ("have you seen the old man...?" That's me.)