"Careful observation and note-taking are the key elements in writing or revising a good walking guide," says David, seen here working on Jarrold's Short Walks guide to Sussex & South Downs.

Many authors use dictation machines or palm computers but, after trying both methods, David still prefers to rely on pen and ink. "All three methods have their advantages," he says, "but the traditional approach works best for me, both in the field and back at my desk. What's more, I never have to replace a battery!"

Neverthless, batteries are essential for David's hand-held GPS receiver. The next generation of Jarrold walking guides include global positioning readings at key stages of every walk, and David has been supplying the company with GPS data since 2004.

Jarrold regularly calls on members of the Outdoor Writers' Guild to help update their market-leading series of Short Walks and Pathfinder walking guides.

In the past, David has worked on a variety of titles, including Hampshire & New Forest, Kent, and In & Around London.