I found The Map That Came To Life while scouting about for Ronald Lampitt. He illustrated my favourite Ladybird book Understanding Maps and this is in a similar vein, but even better. Published in 1948 it tells the story of John and Joanna, stuck at their uncle's for 4 weeks during the summer holidays. He sends them out into the open countryside with only an Ordnance Survey map for comfort.
As they wander along it explains what the markings and symbols mean. Learning about OS maps was one of my favourite things at school - I could look at maps all day. This is a really exquisite combination of fact and decoration. I love the cleanness of it all and the beautiful bright mid-century colours. Oh, and the ragged edges around the text. Nice touch.
I'd love to tell you all about Ronald Lampitt but can't find out too much about him. He did a few travel posters, a few Ladybird books and some other prints, mostly architectural in nature. There are some more pictures from the book in this Flickr set. Happy trails.
Update: Thanks to Daniel Weir for pointing out that scans from the whole book are available on The Alphabet of Illustrators. I'd forgotten about that site - it's very good, if a bit idiosyncratic in the way it's laid out. There's a short bio and some other Lampitt bits and pieces.