A rare stamp with minor condition defects will typically realise only 60 per cent of catalogue value at auction, whereas a pristine example could sell for double the catalogue price.

It might be a rare stamp, or two or three not so rare stamps.

Note that the cost of production may be close to zero, as with a rare stamp, so that the entire price consists of scarcity rent.

The firm runs investment schemes that buy rare stamps to provide a return for investors.

He said that this 'demonstrated that the rerating of rare stamps in the overall collectibles market has increased the natural pressures on supply and demand'.