What wood are they usually made from?

Oak leads by a distance, named in around two in five titles, with mahogany second. Together they account for the great bulk of stated timbers. The archive has also thrown up elm, ash, beech, walnut, rosewood, satinwood, teak and Burmese padouk. Those turn up in ones and twos rather than as a run.

How old are most antique swivel chairs?

The dated field spans exactly a century, 1860 to 1960, and 217 of the 365 listings carry a clean year. The bulk sits either side of 1900. The 1920s is the busiest single decade in the record, ahead of the Edwardian and Victorian labels. The 1930s carries only nine listings, and pre-1870 pieces amount to a couple of entries at 1860.

Are ships' chairs a separate thing?

They're a small, recurring branch of the same category. Titles include carved oak ships chairs, a cast-iron and oak upholstered one, a cockpit desk chair and a pair attributed to a passenger liner. They sit at the very top of the range on Sellingantiques, well above the ordinary desk chairs.

Do swivel chairs come in pairs?

Rarely. The archive shows a set of four late 19th century oak library desk armchairs and a handful of pairs, against hundreds of singles. When they do appear, multiples occupy the top quarter of the range.

Which chairs are not desk chairs?

A few revolving forms were made for other jobs. Music chairs in rosewood and satinwood, an adjustable dressing-table chair, a harpist's chair, and a valet stand fitted with swivel drawers. They come up perhaps once or twice a year, so the desk chair is what you'll meet nearly every time.

How many turn up for sale each year?

About 37 swivel chairs are listed on Sellingantiques in a year. Over the whole record, 104 different dealers have handled one. That means almost every dealer who has sold one has sold only one or two, so it isn't a category anyone specialises in.