Designing a stamp for the Post Office is no way to make a packet. Its head of design, Barry Robinson, pays a flat fee of pounds 1,000 for the artwork of each stamp he commissions. Most special issues involve just four stamps.

But, if the financial rewards are not enticing (certainly to established artists or big design companies), there are compensations: what other organisation can guarantee to print and sell 75 million copies of a designer's work? 'Christmas issues sell five or six times this number,' Mr Robinson says. What better advertisement for your skills? If only the Post Office paid royalties.

Mr Robinson's design department is a small and efficient 'backroom' team whose work enhances our daily life. Year in, year out, it produces some of the world's finest stamps, and these unsung public-service heroes win international design and philatelic awards. This week's issue of railway stamps, for example, is Post Office design at its best: crisp, clean, imaginative and - because they are eye-catching - guaranteed to be popular.

Each image is surrounded by perforations that serve the purpose of a frame around a painting, so each is a tiny work of art. Like fine-art prints, they are beautifully reproduced. 'We use up to seven colours,' Mr Robinson says. 'We print using a photo-gravure process for most stamps. It is not a cheap technique, but then we print in exceptionally high numbers. For the high-value 'Castle' stamps (based on a series of photographs of British castles taken by the Duke of York) we use intaglio, so the stamps are miniature engravings.'

Who chooses the designs? 'The subjects for special stamps are selected after one of the most democratic processes. The Post Office listens to suggestions by literally hundreds of groups and thousands of individuals.'

Ideas are put to the Stamp Advisory Committee (members include Dick Negus, the man behind the livery of British Airways jets, Lady Casson, and John McConnell of the design consultancy Pentagram), which meets 10 times a year and selects nine special-issue subjects for the main Post Office board to approve.

One of the nine is always a Christmas issue, and a second is decided in agreement with the postal services of Europe. The board listens to views from Scotland, Wales and Northern Ireland and finalises a list. This is handed to Mr Robinson, who then commissions three designers for each set of stamps. One of the three is chosen to do the final design.

'Most designers and artists are flattered to be asked,' says Mr Robinson. 'We rarely get a refusal. Sometimes well-known artists don't like the idea of having to compete; they want a direct commission or nothing. John Piper turned me down some years ago, which I thought was a great loss. On the whole, the challenge of designing a stamp is too good a challenge to refuse.

'We don't stick with specific designers. Our policy is to use as great a variety of people as we can. We keep in touch with art colleges to see what trends are developing in art and design as well as to spot up- and-coming talent.

'We have a totally free hand in who we commission. There is no age limit; we've asked children to design stamps for us twice in recent years (a Christmas issue and a set of 'green' stamps in 1992).

'We give designers a sheet of blank stamps to work with; some bring in their ideas at stamp size, but most prefer to work at slightly larger than postcard size. We've had no trouble getting Turners on to stamps, so, although we think small, we can cope with artwork from the Lilliputian to the Academic.

'There are, however, a number of rules and restrictions. The Queen's head, for example, must appear on the stamps in a 'superior position' - at the top - and she cannot be too small. She faces either way, but always into the design. Ideally, she faces the same way throughout a set of stamps.'

The definitive issue of basic stamps - the range simply featuring the Queen's head - dates from 1967. 'It is based on a bust sculpted by Arnold Machin and we call the stamps 'Machin Definitives'.' They are unlikely to change again during the Queen's reign. The image of Queen Victoria survived from the Penny Black of 1840 until her death in 1901.

Are special-issue stamps designed principally to satisfy the stamp collectors? 'No. They are meant to be used for everyday post. Occasionally we produce a set of stamps in which one design flows across the lot. This was true, for example, of the 'Battle of Britain' issue of 1965 and I suppose you could say that these are more or less specifically collectors' items.

'Stamps serve other functions; they are close to being a currency. They also have an ambassadorial role when they travel abroad, representing specific British concerns and attitudes. And, of course, from a strictly commercial point of view, they are a profitable enterprise for the Post Office.'

With luck the Post Office - which is under government review - will escape privatisation, which in Britain, at least, always seems to lead to the lowering of design standards. But if it does go ahead to become more aggressively commercial, will future special-issue stamps commemorate out-of-town superstores, hamburger chains, theme parks, the deregulation of public services, country clubs and 'back to basics'?

To date, the Post Office has retained its dignity, and Mr Robinson and his team offer noble work to British designers. The best way we can support them is to continue to spit on their work, thump it with a fist, chuck it into the post box and send it around the globe.

(Photograph omitted)