The colourful work, called Fete Champetre, sold for pounds 11,875, against its original estimate of pounds 6,000-8,000.

He invented the Fete Champetre, a pictorial form which allowed him to disperse preconceived, and possibly already delineated, images of people of fashion over a wide space of parkland.

By joining a National Trust working holiday, available this year in more than 400 locations from pounds 50 upwards, volunteers learn new skills such as dry stone walling and footpath laying and can get drawn into preparing great events such as the famous Fete Champetre in Stourhead Gardens, Wiltshire.