I was asked by a friend where he could best see, and possibly buy, Old Master drawings.   I thought the best place would be Colnaghi’s, one of the oldest established dealers.   I hadn’t realised that it goes back to 1760, when Giovanni Battista Torre opened a shop in Paris which sold books and prints alongside barometers and fireworks.   His son Anthony opened a print shop in London in 1767, just before the Royal Academy was founded.   It was acquired by Paul Colnaghi in 1788.   Originally based at 132, Pall Mall (in the eighteenth century the art trade was based round Waterloo Place and only moved north of Piccadilly when the RA opened in 1868), Colnaghi moved to Cockspur Street in 1799, where he held three o’clock levées for the world of fashion.   In 1911, the firm moved to 144/6 New Bond Street when Otto Gutekunst was making a fortune, working with Berenson in supplying paintings to the great American collectors.   They are still in Bond Street, but now upstairs.