How do you know if that old sewing machine you have at home is valuable?

According to Mr Christopher Proudfoot, a director of Christie's, there is a very simple rule: "if it's made by Singer it's almost certainly not going to be of any value because Singer was the leading manufacturer. They turned their machines out in millions."

Other companies produced similar machines, which had in common a fixed wooden base about an inch and a half thick. "If it's one of those, it ain't going to be worth much," he says.

Sewing machines of most interest to collectors generally date from between 1860 and 1890 "and they're mostly ones that were made in competition with Singer and to significantly different designs", he says.

One example of an alternative design is the dual purpose late 19th century Ward's Arm and Platform sewing machine. It has a flat bed and also an arm for sewing things like sleeves on. It is "a pretty distinctive looking thing" and one such machine in a Christie's auction on July 28th is estimated at £500 to £800 sterling (€766 to €1,225).

Most old sewing machines "had elaborate gilt decoration on them. And the condition of that decoration is very important to collectors. It's not something you can restore. If it's worn off, that devalues the machine quite a bit."

Prices fetched for old sewing machines range from about £20 sterling for a Singer up to about £5,000 for more sought-after items. "I think I've heard of £8,000 or £9,000 being paid on occasion," he says. One sewing machine sold for £20,000 but that was a very special one. It had been made for Queen Victoria's eldest daughter and was "all silver plated, engraved with pictures of Windsor Castle and carved with eagles".

Its value was due to the fancy effects and the royal connection rather than the sewing machine design. "So up to about £5,000 is the normal range," he says.

Like the Singer, the Wheeler and Wilson machines "aren't terribly valuable because they were again major manufacturers, although there are some variations which can be a bit more valuable".

A US hand sewing machine in the forthcoming auction does not look at all like a sewing machine. Known among collectors as a scissors type, it's "like a pair of pliers or a pair of gardener's secateurs".

You hold it in one hand with the material you are sewing in the other hand and "you just squeeze it to operate it. That's a classic example of something which is totally different in appearance". Dating from the 1880s, it is estimated at £800 to £1,200.

Meanwhile, the Little Europa, which dates from the 1870s or 1880s, is estimated at £800 to £1,200. It is again "a different design from the Singer type. Part of its interest lies in the fact that it was made by a firm which also made bicycles and went on from bicycles to what became the Rover car company".

Sewing machines are usually in working order and, if they are not, "collectors generally like to put them into working order and sew a bit of cloth to see if they can do it".

Mr Proudfoot says there are collectors who exclusively collect sewing machines and agrees that is it amazing the variety of objects that people collect, adding: "Pretty amazing yes, but then I collect old lawnmowers, which is even more amazing."

Readers can contact Mr Christopher Proudfoot at 0044 171 321 3272.