Excitement and intrigue are not what you would usually associate with the often staid world of stamp collecting.

But Steve Stevens, 72, was in for both when he took his misprinted book of stamps along to an exhibition in Norwich.

After nearly 65 years of careful collecting, it seems the Dereham enthusiast may have come across his most unusual – and valuable – stamps quite by chance.

Mr Stevens bought the book of six limited edition first class stamps from the town post office in 2005 and didn't notice anything was out of the ordinary until he got home.

As he put his new stamps in an album, he noticed two were missing the Queen's head and a further three had 'albino' heads rather than metallic silver.

'It was quite exciting to see,' he said. 'I put them away and left them because I've had medical problems. I recently got my albums out again to get them valued and just happened to notice them.

'They had just been sitting there while I wasn't well. My family couldn't believe it.'

Finding such an error is rare and he was persuaded by his family to take the stamps to the Norfolk and Norwich Philatelic Society's centenary exhibition at the Forum earlier this month.

Mr Stevens, a retired station warden at RAF Marham, showed the book to society member Tony Hender, who quickly got to work investigating the faulty stamps and what they could fetch at auction.

The Fakenham-based stamp dealer said: 'I was very excited, but I had to err on the side of caution. It could be that they are worth thousands, but it's all a question of validating them now.'

Ian Billings, of Norvic Philatelics, based in Dereham, said Mr Stevens' booklet had been a hot topic of conversation at the exhibition and specialist dealers had since been consulted.

The value of the stamps depends partly on how many misprinted books were issued and early indications suggest that the faults have not previously been reported.

It is unlikely Mr Stevens' book was one of a kind, but is possible that less eagle-eyed customers failed to spot the variations and posted the stamps as usual.

'I'm told no one has heard of this before,' Mr Billings said.

'One or two major dealers and collectors will be interested, but quite how many zeros there will be I don't know.

'There's always a market for the unusual. When the Victoria Cross stamp was issued in 2006, some of them were missing the Queen's head. That book sold for more than �5,000 at auction.'

Mr Stevens was contacted the day after the exhibition by a member of the Machin Collectors Club in Sutton Bridge who was keen to drive down and take a look.

'I was at our caravan in Mundesley,' he said. 'He got all excited so I said he could come and see it the following day.'

Any money raised through the sale of the stamps will go to Mr Stevens' grandsons who have been helped to start their own collections.

'I would like to see more young people collecting,' he added. 'My story might encourage them to take it up.'

daisy.wallage@archant.co.uk