Swallows and Amazons First illustrated edition 1931
Jonathan Cape, London - hardback
Dedicated to "The Six for whom it was written in exchange for a pair of slippers". After the first edition was published with no illustrations Clifford Webb (1895-1972) was commissioned to illustrate both Swallows and Amazons and the new Swallowdale. In general the effect was admired, although Ransome later complained about their inaccuracies. Webb's drawings were replaced by Ransome's own in 1938. Full details of the first edition here.
This edition is almost as rare as the first edition, but sells for less, possibly up to £2000 depending on condition.