Among the items taken from Altea Gallery was a fourth state of Johannes De Ram’s map of London (1729), first published c.1690.

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Three dealers have been targeted. The latest break-in took place at around 2am on December 4 at Altea Gallery on Saint George Street when 48 antique maps were stolen with a retail value well in excess of £100,000.

Altea Gallery’s director Massimo De Martini said: “This was a typical smash and grab – they were in and out within 90 seconds. They were captured on the CCTV but they were fully masked so you cannot see faces.”

Well rehearsed

“The thieves were very well rehearsed – it was smooth and quick. I think it is a strange thing to target me. We see this sort of thing in jewellery but not antique maps.

“I have been here 20 years and, of course, we may get fraudulent purchases or shoplifting, but not this brutal forced entry.”

In September, a similar theft took place at fellow rare book and map dealer Robert Frew in South Kensington when around 15 items were taken. The thieves smashed their way in with a concrete pedestal taken from temporary fencing nearby. A similar method was used at Altea.

Frew said: “The mode of entry was identical and the time of day was very similar at around 3am. They smashed two glass display cabinets and grabbed everything they could very quickly.

Thankfully my insurance firm Richard Thompson Ltd have been so helpful and understanding.”

An attempted break-in took place at another shop in central London this autumn.

All the dealers involved are members of The Antiquarian Booksellers’ Association (ABA).

President Roger Treglown said: “Book theft is normally a matter of shoplifting, rather than smash and grab. To see the shops of three ABA members targeted within weeks of one another is unprecedented.

“It may be the same gang, or it may signify a worrying trend. Lockdown may have closed off some of the more usual criminal avenues, and there has been widespread recent coverage of valuable stolen books. The thieves haven’t displayed any particular knowledge: they seem to have grabbed anything which looks as though it might be valuable.

“As we’ve always said, and as the recent recovery of the books stolen from a warehouse in Feltham in 2017 demonstrated, it is almost impossible to sell this sort of stolen material on the open market – they are too distinctive.

“There is no thriving black market and they can’t be melted down. After three years the books from Feltham were still buried under a floor in Romania. We hope for the swift recovery of the books and maps stolen from our col leagues, and in the meantime we must all be on our guard.”

A full list of stolen items has been circulated by the ABA.

Anyone with information should call 101 quoting the Metropolitan Police crime reference number 6550608/20 for Altea Gallery and 5613952/20 for Robert Frew. Or call Crimestoppers anonymously on 0800 555 111.