tubechallenge.com

If you are going to attempt the challenge as the OP described it - having to visit every street on the board - then it should definitely be open to all modes of public transport. You wouldn't need to say "visit this Tube station", because it would be every challenger's own decision how they get to the relevant streets.

A lot of the properties are close to each other so I suspect a lot of the challenge would be done on foot, or maybe catching a bus for a stop or two.

Have any of you read this book? I have.

I've read it.

I have that in the attic somewhere, need to dig it out for my girlfriend.