Wanted: Two stolen Old Masters, worth £10m each. Reply to 'Exchange & Mart'

When private detectives and six-figure rewards have failed, what else can two aristocrats do to recover their stolen masterpieces? The answer, it seems, is to enlist a reformed criminal and place an advert in Exchange & Mart.

That is the tactic chosen by two flamboyant peers, the Marquess of Bath and the Marquess of Cholmondeley, to recover paintings burgled from their country houses. An art recovery firm to which they have turnedhas employed a jeweller who was jailed five years ago for "fencing" stolen antiques, including a £4m Rembrandt from the Earl of Pembroke.

David Duddin, 57, was approached by Charles Hill, a former detective chief inspector in charge of Scotland Yard's art and antiques unit who has set up a private consultancy to recover stolen works. He helped recover Munch's Scream while with the Yard. Mr Duddin, who was released on parole last August, insists that he is a changed man and has vowed to use his expertise to try to retrieve the works. He gets a fee if they are returned.

He persuaded his employers to take out an advert in Exchange & Mart, more usually associated with sales of second-hand Ford Escorts than Old Masters. Mr Duddin, of Benton, Newcastle, said: "I suppose it is a drastic measure that two aristocrats have had to advertise in Exchange & Mart for their family heirlooms. What I am doing is helping to get these paintings back to their rightful owners."

The first of the paintings, Titian's Rest on the Flight to Egypt, was stolen in 1995 from the Marquess of Bath's Longleat estate in Wiltshire. It is worth at least £10m, but is so well known that it is unsaleable. The White Duck, by the French artist Jean-Baptiste Oudry and worth between £5m and £10m, was taken from the Marquess of Cholmondeley's Houghton Hall estate in Norfolk.

Despite suggestions that a professional gang were behind a rash of high-profile burglaries at country houses during the Nineties, no one has been caught for the raids on Longleat and Houghton. Criminals are thought to hide the works for years hoping they can be sold unnoticed or used as collateral for other activities such as drug sales.

The Marquess of Bath is renowned for his 73 mistresses, or "wifelets"; and the Marquess of Cholmondeley, who prefers to be known as David Rocksavage, makes films.