This sketch is taken from Towler Hill, a high bluff over the River Tees about a mile north-north-west of Barnard Castle, looking downstream to the castle and town. Towler Hill was a popular viewpoint. Almost exactly the same view was painted in 1805 by John Sell Cotman in a well-known watercolour (Leeds Museums and Galleries)1 while Walter Scott celebrated the prospect in his poem Rokeby published in 1813. Presumably Turner had the poem in mind as he sketched in 1816.
For Barnard Castle in this sketchbook see folio 32 recto (D11493).
David Hill, Cotman in the North, 2005, p.129 reproduced.