h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I've always been a fan of the Lone Pine series, and it seems a shame that this entry is so short.
One of the joys of the series is the real locations - even the 'fictional' sites are thinly disguised versions of genuine places, for instance the Dolphin is quite obviously Rye's Mermaid inn.
The relationships between the characters are far more realistic than most childrens adventure stories, and another element of realism is that it's rare for all the Lone Piners to appear in one book.

The Malcolm Saville society (I forget their official title) has a chap who leads walks around the Long Mynd and Craven Arms, visiting many of the real locations in the books. I think only Witchend itself is completely fictional.

The society is actually called the Malcolm Saville Society. It arranges walks and functions across the country at various locations from the books, especially Rye and the Shropshire areas.
The house Witchend exists, it can be found just past Ingles farm! - But seriously, it is in the exact place that the books show it to be, just under a different name, as is the farm, and the name of the village.