 Merrill is author of more than 430 walking guides which he prints and publishes himself, and his book sales are in excess of 4 million.His best known work is possibly "‘Turn Right at Land’s End’" about his walk around Britain’s coastline.He has created many long distance walks including The Limey Way, The Peakland Way, and Jennifer's Challenge Walk and more than 50 Day Challenge walks which have been used to raise more than £1 million for different charities.