FEW, IF ANY, of the well-heeled, hedonistic young Londoners who use the splendid sports facilities of the Hurlingham Club - gym, swimming pools, tennis courts and croquet lawns - are aware of the rather different function that the Putney site performed during the First World War. In those distant days the Hurlingham was the Naval Ballooning School, where one William 'Pink Tights' Pollock perfected the use of balloons as weapons of war, and made possible the daring flight which lies at the heart of Janet Morgan's engrossing spy story.

Pollock is one of a large cast of brave, resourceful, and frankly eccentric characters that we meet in Morgan's pages. (His nickname derived from the colour of the woolly combinations he wore during his aerial adventures.) At its most basic level, the book is a nail- .-. 1 biting account