Peake also wrote poetry and literary nonsense in verse form, short stories for adults and children (Letters from a Lost Uncle), stage and radio plays, and Mr Pye, a relatively tightly-structured novel in which God implicitly mocks the evangelical pretensions and cosy world-view of the eponymous hero.

Peake first made his reputation as a painter and illustrator during the 1930s and 1940s, when he lived in London, and he was commissioned to produce portraits of well-known people. A collection of these drawings is still in the possession of his family. Although he gained little popular success in his lifetime, his work was highly respected by his peers, and his friends included Dylan Thomas and Graham Greene. His works are now included in the collections of the National Portrait Gallery and the Imperial War Museum.

In 2008, The Times named Peake among their list of "The 50 greatest British writers since 1945". Peake's grandson is rising UK chart star, British musician and singer-songwriter Jack Peñate.

Mervyn Peake was born of British parents in Kuling (Lushan) in Jiangxi Province of central China in 1911 only three months before the revolution and the founding of the Republic of China. His father Ernest Cromwell Peake was a medical missionary doctor with the London Missionary Society of the Congregationalist tradition and his mother, Amanda Elizabeth Powell, had come to China as a missionary nurse.

The Peakes returned to England just before World War I in 1914 but returned again in 1916 to China. Mervyn Peake attended Tientsin Grammar School, where he wrote in 1921 his first novel The White Chief of the Umzimbooboo Kaffirs, until the family returned to England in 1923 via the Trans-Siberian Railway. Mervyn Peake never returned to China but it has been noted that Chinese influences can be detected in Peake's works, not least in the castle of Gormenghast itself, which in some respects echoes the ancient walled city of Peking (Beijing) as well as the enclosed compound where he grew up in Tientsin (Tianjin). It is also likely that his early exposure to the contrasts between the lives of the Europeans, and of the Chinese, and between the poor and the wealthy in China also exerted an influence on the Gormenghast books.

His education continued at Eltham College, Mottingham (1923-1929), where his talents were encouraged by his English teacher, Eric Drake. He completed his formal education at Croydon School of Art and at the Royal Academy Schools from 1929 to 1933, where he first painted in oils and wrote his first long poems. He first exhibited at the Royal Academy and with the so-called "Soho Group" in 1931.

His early career in the 1930s was as a painter in London, although he lived on the Channel Island of Sark for a time. He first moved to Sark in 1932 where his former teacher Eric Drake was setting up an artists' colony. In 1934 he exhibited with the Sark artists both in the Sark Gallery built by Drake and at the Cooling Galleries in London. In 1935 he exhibited at the Royal Academy and at the Leger Galleries in London.

In 1936 he returned to London and was commissioned to design the sets and costumes for Insect Play and his work was acclaimed in The Sunday Times. He also began teaching life drawing at Westminster School of Art where he met painter Maeve Gilmore, whom he married in 1937. They had three children, Sebastian (b. 1940), Fabian (b. 1942), and Clare (b. 1949).

He had a very successful exhibition of paintings at the Calmann Gallery in London in 1938 and his first book, the self-illustrated children's pirate romance Captain Slaughterboard Drops Anchor (based on a story he had written around 1936) was first published in 1939 by Country Life. In December 1939 he was commissioned by Chatto & Windus to illustrate a children's book, Ride a Cock Horse and Other Nursery Rhymes, published for the Christmas market in 1940.

At the outbreak of World War II he applied to become a war artist for he was keen to put his skills at the service of his country. He imagined An Exhibition by the Artist, Adolf Hitler, in which horrific images of war with ironic titles were offered as 'artworks' by the Nazi leader. Although the drawings were bought by the British Ministry of Information his application was turned down and he was conscripted in the Army, where he served first with the Royal Artillery, then with the Royal Engineers. The Army didn't know what to do with him. He began writing Titus Groan at this time.