Mrs Wrigley, a housewife, added: "His vocabulary is amazing. He's able to construct complex sentences.

"The other day he said to me, 'Mummy, sausages are like a party in my mouth'."

Dr Peter Congdon, who assessed Oscar, said he was a "child of very superior intelligence".

"His abilities fall well within the range sometimes referred to as intellectually gifted. He demonstrated outstanding ability," he said.

John Stevenage, Mensa's Chief Executive confirmed Oscar had been accepted aged two years, five months and 11 days.

"Oscar shows great potential. Converting that potential to achievement is the challenge for his parents and we are delighted that they have chosen to join the Mensa network for support", he said.

The youngest British child to join Mensa is Elise Tan Roberts, from Edmonton, North London, at two years, four months and 14 days, with an IQ of 156.

Marilyn Monroe's IQ was higher than Einstein's, even mine is, there's more to genius than a high IQ, something that can't be measured by a simple test.