The heroic efforts of the RAF against the Luftwaffe in 1940 ensured the Nazis never got a toehold on our island nation.

But ask the average adult about the Battle of Britain today and one in three is likely to say they have never heard of it.

A poll reveals a shocking lack of knowledge about the turning point in the Second World War, when The Few denied Hitler’s forces the air superiority they needed to have any chance of launching a ground invasion.

Iconic: But many Britons are now ignorant about the importance of the Battle of Britain

The survey also found an alarming lack of understanding when it comes to many other defining moments of both world wars.

Almost two in five have never heard of the Battle of the Somme in the First World War, while one in eight did not know the Second World War started in 1939 and ended in 1945. One in 20 even believe Germany was one of Britain’s allies and fought on the same side in both conflicts.

Researchers found one in eight Britons are unaware of D-Day and what it marked, and one in five had not heard of the tragic story of Anne Frank.

The study also found a quarter are not aware of the significance of the poppy fields in the First World War, while more than half (54 per cent) are clueless about the disastrous Gallipoli campaign of 1915-16 in which British, French and Anzac forces took on the Ottoman empire.

The survey of 2,000 adults illustrates a dwindling knowledge of recent history and important conflicts of the last century. The statistics emerged in a study by the makers of The Water Diviner, a film directed by and starring Russell Crowe, which is based on the Gallipoli campaign.

Heroes: Some of 'The Few' who protected Britain rushing to their planes during the hostilities

A spokesman said: ‘The two world wars shaped the country into what it is now and are both a huge part of our history. So it’s worrying to see so many people have such little knowledge about what happened during the two conflicts.’

Researchers also found one in ten adults thought a good grasp of world war history was no longer relevant because it was in the past. Three in four Britons admitted they are only aware of many events because they featured in a film or TV programme.

The survey also found that only about half know that Neville Chamberlain was Britain’s prime minister at the start of the Second World War.

Half have no idea about the Nazis defeat at Stalingrad in 1942-43, while even the term VE Day drew blanks from one in four people.