Quote Originally Posted by Muddy Retriever View Post
Sounds like folly to me.

I've done the Fellsman two weeks after the 3 Peaks but I wouldn't do it six days after a marathon. I suppose it depends to some extent on how fast you intend doing London.
Folly indeed, but probably feasible. I'm pretty unfit as far as ultra-marathon runners go, but a couple of years ago did the High Peak Marathon, and then a week later the Wuthering Hike, which I finished in a respectable time (faster than the previous time I did it).