Antiques “knocker boys” are trying to dupe the elderly into selling heirlooms for a fraction of their value.

Police received two reports of cold-callers in Brighton and fear more pensioners may have been targeted but not come forward.

It is the unwelcome return of a practice that blighted the city for decades as police struggled to prove transactions were not in good faith.

Officers are now warning people to be on their guard and to report any suspicious activity.

A 90-year-old man in Surrenden Road was visited on Tuesday at about 4pm.

He saw a man looking through his window, but when he challenged the stranger he talked his way inside.

The man offered him £100 for a painting which had been valued at thousands of pounds.

The man was described as white, in his late 50s, 5ft 10in, of proportionate build, with a missing front tooth.

No sale was made but the man promised to return.

Police are linking it to a visit paid to an elderly woman in nearby Balfour Road, Brighton, earlier in the week.

Inspector Rob Leet of Sussex Police said: “The message is, do not let anybody into your house you do not know.

“If you have elderly neighbours or elderly relatives speak to them and reiterate that messages.”

“Knocker boys” were once a common feature both of the antiques trade and the criminal courts, as teams travelled the country trying to get hold of high-value art or antiques by persuading their owners to accept a very low price compared to their real worth.

Brighton was a hub for the activity in the South East, with “knockers” travelling across the country before bringing back their wares to sell through the town’s antique shops.

In July Anthony Blok, a 72-year-old London solicitor, was jailed for four years after a trial linked to his dealings with at least two Brighton men he represented.

He was found guilty of trying to help sell a painting worth £500,000, which had been bought for £300 from an elderly woman on the Isle of Wight for Blok was also convicted for failing to inform police about £30,000 later seized by police as proceeds of Crime while he was representing another man in 2006.

Anyone with information about the recent visits is asked to call Sussex Police on 0845 6070999 or Crimestoppers anonymously on 0800 555111.