A LOCOMOTIVE discovered in a cottage that backed on to the original Stockton to Darlington railway could be the oldest toy engine in the world. Experts were stumped for a value when Tom Robson took the model engine to the Antiques Roadshow valuation day at Seaton Delaval, Whitley Bay, North Tyneside, in July. Antiques expert Paul Atterbury, who could barely contain his excitement, said the train, which may have been made by a father for his son in the 1820s or 1830s, was worth anything from 20 to 5,000. TNE