Did the Duke of Wellington fake a Waterloo souvenir to present to one of his generals? In 1833, he gave General William Booth, who had been in charge of his commissariat at Waterloo in 1815, a splendid pocket watch engraved "worn by Arthur Duke of Wellington in the war in Spain and at the battle of Waterloo".

Poppycock: Wellington bought it in July 1815 - the month after Waterloo - while strolling round occupied Paris, according to an entry in the archives of Abraham Breguet, the watchmaker who sold it to him. If Wellington did not order the belated inscription, then who did? Booth, perhaps? The watch, with gold-plated movement and gold, three-armed balance, is estimated pounds 20,000-pounds 30,000 at Christie's watch sale, Friday (10.30am).

When was the last time you saw a musical box? Sotheby's has 75 in its mechanical music sale, Thursday (10.30am). The Chinese, Koreans and Japanese love them and prices are firming up. In this sale there are few estimated under pounds 500 and you could pay over pounds 12,000.

Musical boxes, with their plink-plunk steel combs of notes, were developed by clever Swiss watchmakers around the time of Waterloo. The tunes - light opera is common - are full of expression. Those groovy old watchmakers varied the position of the pins by hairsbreadths to produce rubato - a bending of tempo.

By the turn of the century, cheap removable discs had replaced cylinders, which were usually built-in. Penny-in-the-slot disc musical boxes became the first juke boxes. They were short-lived. By 1905, something called a phonograph, invented by a Mr Edison, had become popular.

A German Enigma code enciphering and deciphering machine of about 1940, looking like a bulky desk-top computer, is estimated pounds 8,000-pounds 12,000 in Sotheby's scientific instrument sale, Friday (10.30am). When the boffins of Allied Intelligence cracked it, D-Day was brought forward by two years.

There are over 400 lots of clocks this week at Sotheby's, Thursday (10.30am) and Christie's South Kensington has about half that number on Friday (2pm). At Christie's: a foot-high novelty 1945 Bakelite electric clock, like a television set, with a rocking three-masted sailing ship in an illuminated day/night simulation inside the screen: est pounds 200-pounds 400.

A rare sword that belonged to Tipu Sultan, the 18th-century ruler of Mysore who vanquished the British, is estimated pounds 3,000-pounds 5,000 at Christie's sale of antique arms and armour, Wednesday (11am).

John Windsor