Investment interest in sectors such as stamps, fine art, fine wine and antiques has increased in recent years amid a hunt for "real assets" at a time of concern about the risks of inflation and poor performing mainstream markets.

With this in mind, venerable London firm Stanley Gibbons has launched a Flexible Trading Portfolio in response, the firm says, to market demand.

The product is a portfolio of rare stamps compiled by Stanley Gibbons’ experts with no tie-in period: individual items or the entire portfolio can be sold at any time or more can be bought.

Stanley Gibbons provides free storage, valuations and insurance during the term of the investment.

Investors’ return is determined by when they sell after the purchase date: up to one year, 30 per cent of the profit; 1 to 3 years 50 per cent, 3 to 5 years 70 per cent and over 5 years 80 per cent.

“We believe our new portfolio gives investors a product where they can benefit from the underlying stability and strength of the rare stamp market, but with the ability to top up and trade in a way that is familiar to them from their mainstream investments; so, safe haven investing but with flexibility,” said investment director Keith Heddle.