AN EXTREMELY rare Rupert Bear annual is expected to fetch up to £23,000 when it goes under the hammer in the Cotswolds later this month.

The 1973 book has an illustration on the cover showing the much-loved children’s character with a brown face, instead of the usual white face.

It is one of only 12 printed with the brown-faced Rupert – making it ultra rare and has caused a stir among collectors across the world ahead of the auction on Thursday, June 17.

The Daily Express newspaper started publishing Rupert’s adventures in 1920 and printed both comic strips and annuals.

Illustrator Alfred E Bestall always depicted Rupert on the annual’s cover with a brown face, whereas inside the book the bear’s face was always white.

But in 1973, after a dozen copies of the brown-faced annual had been printed, the newspaper’s editor stopped the presses and changed the cover so Rupert had a white face – without consulting illustrator Bestall.

Some say the editor did this because he had been bombarded with letters from children asking why Rupert had a brown face on the cover and a white face inside, others say he thought the brown face blended into the background too much.

When Bestall realised the change had been made, he was incensed at not being consulted, left in protest and never drew another cover for a Rupert annual.

Half a million copies of the 1973 white-faced Rupert annual were printed – compared to only 12 brown-faced annuals.

Auctioneer Chris Albury of Dominic Winter Auctions in South Cerney, says only four of these annuals have ever come to light, describing it as ‘the holy grail of any Rupert collection’.

He said: "It's a bit like the stamp or coin market where, due to a printing mistake, the withdrawn and rarer mistake is worth far more than the genuine article."

Two brown-faced 1973 Rupert annuals sold for a staggering £23,000 and £22,000 at auction in Dorset in 2007, setting a new price record.