The first half of the walk is along the Basingstoke and Odiham Canal including a visit to the remains of King Johns Castle. It was from here that King John rode to Runymede to sign the Magna Carta. We leave the Canal at Greywell Tunnel - once the longest canal tunnel in the Country - but now non navigatable due to roof collapses so now home to the largest Bat colony in the UK with over 12,000 Bats. Walking through the pretty village of Greywell we leave via the Church yard and walking across fields to return through attractive Odiham