Dan Jones examines Britain's most iconic canals, beginning with the 152-mile Grand Union Canal, which runs up the spine of the country. Constructed at the height of the Industrial Revolution, the task challenged even the greatest engineering minds of the time, including pioneers such as James Brindley, the man behind Britain's first commercial canal, and William Jessop, the person with whom responsibility lay for the building of the main link from Birmingham to London. Travelling along its route, Dan experiences first-hand the innovations behind its construction, including the Blisworth tunnel