Alan Alexander Milne was born in Kilburn, London on January 18^th, 1882 to parents John Vince Milne, who was Scottish, and Sarah Marie Milne (née Heginbotham). He grew up at Henley House School, 6/7 Mortimer Road, Kilburn, a small public school run by his father. One of his teachers was H. G. Wells, who taught there in 1889–90. 

Milne was a pupil at Westminster School and then Trinity College, Cambridge where he studied on a scholarship, graduating with a B.A. in Mathematics in 1903.  Whilst there, he edited and wrote for Granta, a student magazine. He also collaborated with his brother Kenneth and their articles appeared with the initials AKM.  Milne's work came to the attention of the leading British humour magazine Punch, and he contributed humorous verse and whimsical essays which led to him becoming not only a valued contributor but later an assistant editor.  A keen cricketer, Milne played for the amateur English cricket team the Allahakbarries alongside authors J. M. Barrie and Arthur Conan Doyle.  Bizarrely for such a clever literary group the team thought Allah Akbar meant Heaven Help Us rather than its more rightful definition of God is Great.  During the early part of the century Milne was very prolific; keeping up his numerous article writing as well as 18 plays and 3 novels, including the murder mystery The Red House Mystery (1922).   With life going very well and threat of war on the Continent still seemingly far away Milne married Dorothy "Daphne" de Sélincourt in 1913.  It was to be a long, and by all accounts, happy and devoted marriage.  Despite being a pacifist, in 1915, Milne served in World War I, enlisting as an officer in the Royal Warwickshire Regiment, and then working in the Royal Corps of Signals and later, after a debilitating illness, the Royal Corps of Signals. He was commissioned into the 4th Battalion, Royal Warwickshire Regiment on February 17^th 1915 as a second lieutenant (on probation). His commission was confirmed on December 20^th, 1915. 

On 7 July 1916, during the Battle of the Somme he was injured and invalided back to England. After recuperating, he was recruited into Military Intelligence to write propaganda articles for MI7b, which was responsible for foreign and domestic propaganda and press releases concerning army issues.  With the War’s end he was discharged on February 14^th, 1919, and returned to married life at a house in Mallord Street, Chelsea with his wife, Dorothy.   In 1920 they were expecting a baby girl. When the baby was born a boy, he was named Christopher Robin Milne. 

Milne was an early screenwriter for the infant British film industry, writing four stories, filmed in 1920, for the company Minerva Films, founded that same year, by the actor Leslie Howard, whom he had met when he starred in Mr Pim Passes By, and story editor Adrian Brunel.  These films were The Bump, starring Aubrey Smith; Twice Two; Five Pound Reward; and Bookworms. 

Poetry was next and in 1924 Milne produced a book of children's poems When We Were Very Young, which were illustrated by Punch staff cartoonist E. H. Shepard. A collection of short stories for children Gallery of Children, and other stories that became part of the Winnie-the-Pooh books, were first published in 1925. 

In 1926, Milne reflected on this frenetic period of his life and observed that when he told his agent that he was going to write a detective story, he was told that what the country wanted from a "Punch humorist" was a humorous story; when two years later he said he was writing nursery rhymes, his agent and publisher were convinced he should write another detective story; and after another two years, he was being told that writing a detective story would be in the worst of taste given the demand for children's books. Milne concluded that "the only excuse which I have yet discovered for writing anything is that I want to write it; and I should be as proud to be delivered of a Telephone Directory con amore as I should be ashamed to create a Blank Verse Tragedy at the bidding of others." 

Not yet known as Pooh, the character made his first appearance in a poem, "Teddy Bear", published in Punch magazine in February 1924. 

In 1925, A. A. Milne bought a country home, Cotchford Farm, in Hartfield, East Sussex, and on Christmas Eve that year Pooh first appeared in the London Evening News in a story called "The Wrong Sort Of Bees".  The book, Winnie-the-Pooh, was published in 1926, followed by The House at Pooh Corner in 1928. A second collection of nursery rhymes, Now We Are Six, was published in 1927. All three books were illustrated by E. H. Shepard.   Other work continued to flow from his pen and four plays were published during this period. He also contributed a quarter of the costs of dramatising P. G. Wodehouse's A Damsel in Distress. 

Milne is most famous for his two Pooh books about a boy named Christopher Robin, and various characters inspired by his son's stuffed animals. Christopher Robin Milne's stuffed bear, originally named "Edward", was renamed "Winnie-the-Pooh" after a Canadian black bear named Winnie (after Winnipeg), which was used as a military mascot in World War I, and left to London Zoo during the war. "The pooh" comes from a swan called "Pooh". E. H. Shepard who illustrated the books, used his own son's teddy, Growler ("a magnificent bear"), as the model. The rest of Christopher Robin Milne's toys, Piglet, Eeyore, Kanga, Roo and Tigger, were incorporated into A. A. Milne's stories, two more characters, Rabbit and Owl, were created by Milne's imagination. 

The fictional Hundred Acre Wood of the Pooh stories derives from Five Hundred Acre Wood in Ashdown Forest in East Sussex, where the Pooh stories were set. Milne lived on the northern edge of the forest at Cotchford Farm, and took his son for walks there. 

1. H. Shepard drew on the landscapes of Ashdown Forest as inspiration for many of his marvellous illustrations. The adult Christopher Robin commented: "Pooh's Forest and Ashdown Forest are identical". 

Many popular tourist locations can now be found at Ashdown Forest including: Galleon's Lap, The Enchanted Place, the Heffalump Trap and Lone Pine, Eeyore’s Sad and Gloomy Place, and the wooden Pooh Bridge where Pooh and Piglet invented Poohsticks. 

The success of his children's books was to become a source of considerable annoyance to Milne, whose self-avowed aim was to write whatever he pleased and who had, until then, found a ready audience for each change of direction: he had freed pre-war Punch from its usual facetiousness; he had made a considerable reputation as a playwright (like his idol and fellow amateur cricketer J. M. Barrie) on both sides of the Atlantic; he had produced a witty piece of detective writing in The Red House Mystery. But once Milne had, in his own words, "said goodbye to all that in 70,000 words" (the length of his four children's books), he had no intention of producing any more of them especially given that one of the sources of inspiration, his son, was growing older. 

In his literary home, Punch continued to publish whatever Milne wrote, including the long poem "The Norman Church" and an assembly of articles entitled Year In, Year Out (which Milne likened to a benefit night for the author). 

In 1930, Milne adapted Kenneth Grahame's novel The Wind in the Willows for the stage as Toad of Toad Hall. A special introduction written by Milne is included in some editions of Grahame's novel. 

In 1934 he wrote a denunciation of war titled Peace with Honour (which he retracted somewhat in 1940 in War with Honour). 

During these and later years Milne returned to writing for adults, publishing novels, short-story collections and, in 1939, his autobiography, It's Too Late Now. 

During World War II, A. A. Milne was Captain of the British Home Guard in Hartfield & Forest Row, and insisted on being plain "Mr. Milne" to the members of his platoon. 

He was also one of the most prominent critics of P. G. Wodehouse, who, captured at his French country home and imprisoned for a year by the Nazi’s made several radio broadcasts about his internment, which were broadcast from Berlin. Although the light-hearted broadcasts made fun of the Germans, Milne accused Wodehouse of committing an act of near treason by co-operating with his country's enemy. Wodehouse got some revenge on his former friend by creating fatuous parodies of the Christopher Robin poems in some of his later stories, and claiming that Milne "was probably jealous of all other writers.... But I loved his stuff." 

Milne did not speak out much on the subject of religion, although he used religious terms to explain his decision, while remaining a pacifist, to join the army: "In fighting Hitler", he wrote, "we are truly fighting the Devil, the Anti-Christ ... Hitler was a crusader against God." 

With the War over and the ruin of Europe awaiting re-building AA Milne’s later years were to turn out not to be so productive and always overshadowed by the world wide success of Winnie-the-Pooh.  

He retired to his farm after a stroke and brain surgery in 1952 left him an invalid, and by August 1953 "he seemed very old and disenchanted". It was here that he would spend the rest of his life still reading, leading a sedate, isolated, country life.   

After this long illness, he died on 31st January, 1956. 

As a writer his humour and works were prodigious.  But always the scale of his work would be reduced down to Winnie-the-Pooh.  Soon after its initial publication he wrote "I suppose that every one of us hopes secretly for immortality; to leave, I mean, a name behind him which will live forever in this world, whatever he may be doing, himself, in the next."  Pooh has certainly done that. 

In his will Milne left the rights to Winmie-the-Pooh to four beneficiaries, his widow sold her rights to the Pooh characters to Stephen Slesinger, whose widow sold the rights after Slesinger's death to the Walt Disney Company, which has made many Pooh into a merchandising behemoth. Commercially the character sells billions of dollars of products annually. 

In 2001, the other three beneficiaries, the Royal Literary Fund, Westminster School and the Garrick Club sold their interest in the estate to the Disney Corporation for $350m. Previously Disney had been paying twice-yearly royalties to these beneficiaries. The estate of E. H. Shepard also received a sum in the deal. 

A memorial plaque in Ashdown Forest, unveiled by Christopher Robin in 1979, commemorates the work of A. A. Milne and Shepard in creating the world of Pooh. Milne once wrote of Ashdown Forest: "In that enchanted place on the top of the forest a little boy and his bear will always be playing".