Daleks are planning to invade a Gloucestershire auction room next month - and for investors and auction dabblers seking an unusual punt, their arrival may be very timely.

The emotionless aliens from the BBC's long-running science fiction series, Doctor Who, will go under the hammer in a sale at John Rolfe Auctions in Babdown, near Tetbury, on February 10th to the 11th.

The callous cyborgs first appeared on screen in 1963, but have subsequently thrilled a new audience amid a resurgence of Doctor Who mania after the BBC blew the cobwebs off the show in 2005.

Auctioneer John Rolfe said that the red example is believed to have been part of Longleat's infamous exhibition which terrified successive generations of visitors from 1973 to 2003, while the bronze counterpart is thought to have possibly featured on television in the relaunched Doctor Who series.

Mr Rolfe said: "These have come in privately, with no reserve, so here to be sold in a collector sale. We've got further collector's items from film and television, including some Muhammad Ali photographs."

The red Dalek comes equipped with a seat and controls for its weapons, while further lots on the Whovian theme include a coat in the style of Colin Baker's Doctor, as well as a knitted scarf (à la Tom Baker) which will also go under the hammer in the special collectors' sale.

In December, This is Money reported that with the arrival of Ncuti Gatwa as the fourteenth doctor, the value of time-travelling collectibles is now at a new peak.

The website said: "Now grown up, many with children or even grandchildren of their own, Doctor Who fans – known as Whovians – are snapping up the memorabilia they grew up with."

Prices are accordingly buoyant. The Doctor Who collectibles marketing website DoctorWhoToyBox lists items as diverse as a novelty Dalek cake from Selfridges (with a 1965 sell-by date), for £30, a 1965 "We Command You to Have a Happy Birthday" card, for £50, and a Dalek porridge bowl, from the same year, for £100. A pair of 1965 Furness flock Dalek slippers are also yours for £350.

Complete with an exhibition, the Who Shop in London says it draws customers from all over the world and that business is strong. 

So what's your average Dalek worth these days? 

As guidance, screen-used Daleks are the models that find the best prices. An original 1960s Dalek can be hard to put a price on, but £35,000 has been known, while modern examples can still achieve £4,000 if produced under licence from the BBC.

Alexandra Looseley-Saul, the owner of the store, said: "The secret of investing in Doctor Who memorabilia is to have fun." An emotional connection with the item for sale is what counts for potential resale value - even if that emotion is an impulse to jump behind the sofa.