Art thieves used to carry out risky assignments. Organised gangs would exploit weak security in galleries and homes, targeting valuable antiquities in the knowledge that they would be able to sell them for vast sums of money.
Stolen manuscripts, sculptures and carvings would change hands, eventually passing from the black market into the legitimate international art market to end up in the homes of wealthy buyers unaware of the illegal trail their prized art had travelled.
But changes to legislation, together with police crackdowns,have spelled an end to the days when a stolen work of art could command a high price, the conference in London heard.
In response, the black market has itself grown more sophisticated, according to Mark Dalrymple, director of Tyler and Co loss adjustors.
Stolen works of art are now much more likely to be employed as a form of currency within the criminal underworld.Rather than returning to the open market, they may be used as a financial guarantor, or as payment for drugs or arms.
In one case, a criminal from the north of England was known to have put up a Titian painting to secure a £50,000 cash advance for a bail bond, Mr Dalrymple said.
With paintings harder to sell, the prices thieves can command have been driven down. It is perhaps these more stringent circumstances which have allowed for some remarkable returns of high-profile works to their rightful owners in recent years.
In 2002, a Titian masterpiece, Rest on the Flight Into Egypt, was recovered in a plastic bag at a bus stop. The painting, worth £5m,had been stolen from the Marquess of Bath's Longleat estate in Wiltshire seven years previously. Its return followed a secret operation involving a former Scotland Yard detective and a mysterious figure described as a cross between the television characters Arthur Daley and Lovejoy. The recovery came after Lord Bath made an appeal on the radio, offering a £100,000 reward.
Mr Dalrymple suggested that even a painting such as Madonna of the Yarnwinder by Leonardo da Vinci, stolen from the Duke of Buccleuch's Drumlanrig Castle two years ago, was probably sold for as little as £20,000 within a day or two of the theft.
"People are realising it's not so easy to launder money by using art and antiques," he said. The investigation into the theft of the Renaissance painting, which had been in the family for 250 years, continues, and they have put up a £1m reward for its safe return.
At the time of the theft it was assumed professional criminals were responsible, but detectives now believe the painting was stolen by an opportunist thief.
Galleries are notoriously reluctant to reveal any arrangements privately made for the recovery of stolen works. In mysterious circumstances, the Tate recovered two Turner paintings years after they were stolen from a museum in Frankfurt in 1994.Reuse content