The creator of Paddington Bear has criticised those responsible for putting the world’s best known duffel-coat-wearing immigrant from Darkest Peru in an advertisement for Marmite.

Michael Bond was not consulted about the advert – in which Paddington breaks a lifetime’s reliance on marmalade sandwiches and decides he “ought to try something different” – and feels that it was a mistake.

Fans have been outraged by what they see as a betrayal of the character’s integrity, many telephoning Bond to harangue him. Like them, the author feels that the advert was a mistake because Paddington’s characteristics are “set in stone and you shouldn’t change them”. The bear’s preference for marmalade sandwiches, often stored under his hat is “fundamental”, he said yesterday.

During the 1980s, when Paddington’s popularity was at a peak thanks to the television series narrated by the late Sir Michael Hordern, Bond retreated from the growing commercial operation to concentrate on writing books.

Karen Jankel, his daughter and managing director of Paddington and Company, now has final approval on all merchandising decisions. Despite strong reservations she agreed to the proposal from the Copyrights Group, Paddington’s licensing agents, because she believed the advert would lift Paddington’s profile and bring him back to British TV. But Bond would rather the whole thing had never happened.

“Now there’s no going back,” he said. “Paddington likes his food and tries anything but he would certainly never be weaned off marmalade.”

In a letter published in The Times today, Bond, 81, defends himself against allegations that he sold-out his best-loved creation. He writes of an “ill-founded rumour that I was responsible for the script of a commercial featuring Paddington Bear testing a Marmite sandwich” and “that one of the reasons may have been that Marmite paid me a truly vast sum of money.

“I should be so lucky – particularly since I didn’t write it,” he says. “Although Paddington found the sandwich interesting, bears are creatures of habit. It would require a good deal more than the combined current withdrawals from Northern Rock to wean him off marmalade, if then.”

The advert, by DBB London, features the animation format in which Paddington made his TV debut in 1975. He finds Marmite “really rather good”, before stumbling into a chain of unfortunate events. Uni-lever, the makers of Marmite, hope the campaign will appeal to the nostalgia of older viewers while encouraging younger ones to try the spread.

Nicholas Durbridge, of the Copyrights Group said: “Paddington has always been inquisitive. Now he has tried Marmite. It’s unfortunate if Michael’s not completely happy but Paddington will always be associated with marmalade and our client supported our recommendation to make the advert fully.”

Ms Jankel said last night: “From my father’s point of view, he’s the creator and wrote the books. The Copyrights Group are doing their job, looking to do what they think is best from the commercial point of view. I think Paddington is so strong that he will rise above all of this.”

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