For many years Mark Horrell has been writing what has been described as one of the most credible Everest opinion blogs out there. He writes about trekking and mountaineering from the often silent perspective of the commercial client. For nearly 20 years he has been exploring the world's greater mountain ranges and keeping a diary of his travels. As a writer he strives to do for mountain history what Bill Bryson did for long-distance hiking. His favourite mountaineering book is The Ascent of Rum Doodle by W.E. Bowman.