The Grand Union Canal is a magnificent waterway that links the River Thames at Brentford in London with Bordesley Junction in Birmingham. Not counting the arms, it is 137 miles long and contains 166 locks. There are many buildings and features to note along its length, including Mentmore Towers, once the residence of Archibald Philip Primrose, 5th Earl of Rosebery and Prime Minister in the mid-1890s, and the canalside wall mural at Wolverton, which at 173 yards long is believed to be the longest wall mural in Britain and depicts the town's railway heritage and its other industries. Roger Mason takes you on canal journey from the capital to the nation's heartland detailing the surrounding landscape and wealth of historic features along the way.