He is one of the best-loved children’s characters of all time. But even Paddington’s first editor took a little convincing to fall in love with him, according to a letter which details her “initial suspicion”.

The letter, signed by editor Barbara Ker Wilson and released from the HarperCollins archive to celebrate 60 years of Paddington books, tells how she feared the manuscript would be filled with the “whimsy-whamsy” style she had come to expect from anthropomorphised animals, or based on adult innuendos.

The book had previously been passed over by other publishers, before Ker Wilson found herself “completely won over” by Michael Bond's story.

In a letter dated 29th January 1958 and now made public to celebrate the anniversary, she wrote: “I opened the ms. [manuscript] with initial suspicion - only to find myself completely won over by the author’s simplicity of style, from the first page onwards.

“His direct and simple approach is a refreshing change from the hosts of other mss. which introduce humanized animals, and which are invariably either whimsy-whamsy, written down, or filled with adult innuendos.”