As part of the survey, carried out to mark this week’s 70th anniversary of Churchill’s prime ministerial tenure, more than 1,136 people were asked to identify three prominent 20th century PMs including Churchill, Margaret Thatcher and Tony Blair.

One in five (19%) adults failed to name Churchill, with the figure rising to 32% of 25 to 34-year-olds and 44% of those aged 16 to 24.

Following the pattern, researchers projected the rough date when the leaders would no longer be recognised, with Churchill’s demise predicted in 80 years’ time.

They said the vast majority of those questioned could identify both Mr Blair (97%) and Baroness Thatcher (98%).

But recognition dropped significantly in the 16 to 24-year-old range – 16% failed to identify Baroness Thatcher and more than a quarter (27%) were unable to recognise Mr Blair.