Book excerpt: For more than half a century, a shared love of canals and narrowboats has been inseparable from the marriage of Timothy West and Prunella Scales. The two iconic actors have spent many of the happiest days of their life together enjoying the calming pleasures of watching land and nature unfold before them at four miles an hour. In 2014, Tim and Pru took to the canals of Britain and beyond with a television crew and a brief to record their best-loved trips along the most beautiful waterways they could find. Not only does OUR GREAT CANAL JOURNEYS recount their careers and travels, but it also explores the trials - and the joys - of ageing, and how Prunella's struggle with dementia has both changed, and yet failed to change, their lives together.