He started his acting career in 1940, in a touring company in Cardiff playing a juvenile lead in Sweet Lavender. He went on to join Robert Atkin’s Shakespearean company in Regent’s Park, London, until he was called up for service in the RAF. He was appearing in a Shakespearean play in doublet and hose in the open-air theatre in London’s Hyde Park when two RAF MPs marched on stage and arrested him for desertion. Unknown to him, an RAF conscription notice had been following him for a month as his company toured.

In 1949 he married his second wife Clementina Stuart, a Royal Ballet dancer. They had four children:

In 1951 Bentine was invited to the United States to appear on The Ed Sullivan Show. On his return he parted amicably from his partners and continued touring in variety, remaining close to Secombe and Sellers for the rest of his life. In 1972, Secombe and Sellers told Michael Parkinson that Bentine was “always calling everyone a genius” and, since he was the only one of the four with a “proper education”, they always believed him.

On his return to Britain in 1954, he worked as a scriptwriter for Peter Sellers and then on 39 episodes of his own radio show Round the Bend in 30 Minutes, which has also been wiped from the BBC archive. He then teamed up with Dick Lester to devise a series of six TV programmes Before Midnight for Associated British Corporation (ABC) in Birmingham in 1958. This led to a 13-programme series called After Hours in which he appeared alongside Dick Emery, Clive Dunn, David Lodge, Joe Gibbons and Benny Lee. The show featured the “olde English sport of drats, later known as nurdling”. Some of the sketches were adapted into a stage revue, Don’t Shoot, We’re British. He also appeared in the film comedy Raising a Riot, starring Kenneth More, which featured his five-year-old daughter “Fusty”. He joked that she got better billing.

From 1960 to 1964, he had a television series, It’s a Square World, which won a BAFTA award in 1962 and Grand Prix de la Presse at Montreux in 1963. A prominent feature of the series was the imaginary flea circus where plays were enacted on tiny sets using nothing but special effects to show the movement of things too small to see and sounds with Bentine’s commentary. One, titled The Beast of the Black Bog Tarn, was set in a (miniature) haunted house.

He was the subject of This Is Your Life in April 1963 when he was surprised by Eamonn Andrews at the BBC Television Theatre.

In 1968, travelling on the British Hovercraft Corporation (BHC) SR.N6, GH–2012, Bentine took part in the first hovercraft expedition up the River Amazon.

Of his five children, the two eldest daughters, Elaine and Marylla, died from cancer (breast cancer and lymphoma) in the 1980s. His elder son Stuart was killed with a pilot friend when a Piper PA-18 Super Cub crashed into a hillside at Ditcham Park Woods near Petersfield, Hampshire, on 28 August 1971. Their bodies and the aircraft were not found until October 1971. The AAIB after an 11-month investigation found that the aircraft went into clouds when taking action to avoid power cables while flying low in poor visibility, and subsequently, went out of control. Bentine’s subsequent investigation into regulations governing private airfields resulted in his writing a report for Special Branch into the use of personal aircraft in smuggling operations. He fictionalised much of the material in his novel Lords of the Levels.

From 1974 to 1980 he wrote, designed, narrated and presented the children’s television programme Michael Bentine’s Potty Time and made one-off comedy specials.

From 1975 until his death in 1996, he and his wife spent their winters at a second home in Palm Springs, California, US.

On 14 December 1977, he appeared with Arthur C. Clarke on Patrick Moore’s BBC The Sky at Night programme. The broadcast was entitled “Suns, Spaceships and Bug-Eyed Monsters” – a light-hearted look at how science fiction had become science fact, as well as how ideas of space travel had become reality through the 20th century. In the opening of the programme, Moore introduces Bentine with Bentine confirming that he was the possessor of a “Readers Digest Degree”. This remark was typical of Bentine’s comic approach to most things in life that concealed his knowledge of science. Bentine appeared in a subsequent broadcast on a similar theme with Moore in 1980. Following the death of Arthur C. Clarke, BBC Sky at Night magazine released a copy of the 1977 archive programme on the cover of their May 2008 edition.

In 1995, Bentine received a CBE from Queen Elizabeth II “for services to entertainment”. He was also a holder of the Peruvian Order of Merit (as was his grandfather, Don Antonio Bentin Palamero [es]) for his work leading the fundraising for the Peruvian Earthquake Appeal.