Sale: Incoming Tide: Paintings by John Walker

Location: Offer Waterman, 11 Langton Street, London SW10, tel: +44 (0)20-7351 0068; www.waterman.co.uk

Date: Until November 7, Monday-Friday 10am-6.30pm, Saturday 11am-4pm

Need to know: There is not much new about using “found objects” as a starting point from which to produce art, but the septuagenarian British painter John Walker might just be the first person to eschew a nicely stretched canvas in favour of a discarded bingo card. British-born Walker, who studied at Birmingham School of Art and later in Paris, has been best known for producing large, wall-filling paintings since the 1970s when he made his chalk-drawn “Blackboard” series and later his “Juggernaut” works created from dry pigment.

Now the head of the graduate painting programme at Boston University, he takes his summer vacations along the coast of Maine where, three years ago, he moved into a new studio at Walpole. Among the usual detritus left by a previous incumbent, Walker discovered hundreds of abandoned bingo (or beano) cards thought to date from the 1950s when the building was used as a community centre. His first reaction was to consign them to the garbage but then the 7in by 5in format, complete with printed number grid and playing instructions, suddenly manifested itself as a potential surface on which to paint. The idea for the “Seal Point” series was born.

Highlights: In his introduction to the catalogue for this exhibition, Christopher Riopelle of the National Gallery observes that the landscape oil sketch first came to the fore during the 1770s when two artists, Frenchman Pierre-Henri de Valenciennes and Welshman Thomas Jones, independently began creating small oil sketches en plein air on bits of card. The idea was to produce a quick, loose “impression” of nature, a technique at which John Constable proved especially adept (think of his famous Hampstead Heath cloud studies). Walker’s found bingo cards proved perfect for just such a purpose. He could slip a handful into his pocket, wander out to the Maine shoreline and knock out a sketch in little more than an hour. The result is this selling exhibition of 56 paintings, which are both small and beautifully formed .

It is not feasible to select a highlight as each is as open to individual interpretation as the next and all carry the same £5,000 price tag. Small they may be, but the works are so tactile, free and well-observed that it is difficult not to become mesmerised, especially when Walker allows the bingo numbers to show through. But there is a downside to this show: the pictures look as though they need to stay together, so you might end up trying to buy the lot.