The series has three one-hour episodes

Dunkirk had 4.8 million viewers - more than double the number who saw BBC One's Family Business, which had 2.1 million watching at the same time.

ITV1 show Footballers' Wives attracted 5.3 million viewers, according to unofficial overnight figures.

The second instalment of Dunkirk's three-part series is aired on Thursday.

The 1940 evacuation involved both naval and civilian ships, which rescued 338,000 Allied troops stranded along Dunkirk's beaches as the Germans continued their advances.

"I'm overjoyed, it's fantastic that audiences have validated our approach to tell a factually-based story in an exciting way," producer Rob Warr told BBC News Online.

"I had high hopes for it but I was not expecting it to do that well," he added.

Dunkirk is one of the greatest maritime evacuations in history

Mr Warr said he felt people made an appointment to see programmes like Dunkirk.

"The name of the programme draws people in - my generation have grandfathers who fought in the war so the interest is there across the generations," he said.

The programme stars Olivier Award winner Simon Russell Beale as Winston Churchill, who had been in power for little over a week when he ordered the rescue bid to save the stranded soldiers.

Realistic

The series was shot on locations around Dunkirk, Chatham and Whitstable.

Many Dunkirk veterans were interviewed in order to build up a picture of the events.

"We want to give a very real sense of actually being there: what would you have done? How would you have felt? We hope to give viewers an authentic sense of what living through the events would actually have been like," said Mr Warr while making the programme.

"Filmed like reportage, with a real sense of immediacy, we want viewers to feel very much at the centre of the action," he added.

A BBCi Dunkirk interactive service follows each episode, which includes interviews with British, French and German eyewitnesses telling the true stories of different parts of the Dunkirk evacuation as depicted in that evening's drama.