Rediscovered Turner watercolour bought in a group lot for £100 could fetch £30,000 at Cheffins auction in Cambridge

A newly-discovered early watercolour by JMW Turner is expected to fetch at least £20,000-£30,000 at the Cheffins Fine Sale in Cambridge on 20-21 March.

Depicting the Entrance to Bishop Vaughan’s Chapel in St David’s, Wales, it is signed ‘W Turner’ and can be dated to the artist’s 1795 tour of Wales.

It has been held in a private Suffolk collection for the past 30 years, having being bought in a group lot of paintings for about £100.

The anonymous owner thought it might have been a Turner, and contacted Cheffins, which sold a previously untraced Turner watercolour of Chepstow Castle from a similar period for £93,000 last year. A Turner expert at Tate Britain has verified the painting.

Patricia Cross, associate at Cheffins, says: “This piece is a significant new discovery which provides a glimpse into Turner’s early development as an artist. It is a marvellous example of his architectural drawing in which he demonstrates extraordinary attention to detail and his imaginative understanding of light and dark. It is the true definition of an auction house ‘sleeper’, and we are privileged to be able to offer it to the market.”

Among other lots on sale are a portrait by Sir Godfrey Kneller (1646-1723) of Edward Richard Montagu, Viscount Hinchingbrooke, painted in 1700 when the sitter was eight. He was the father of Cambridge-educated John Montagu, 4th Earl of Sandwich (1718-1792) who is credited with being the inventor of the ‘sandwich’.

The portrait originally came from Hinchingbrooke House and has an estimate of £8,000-£12,000.