The BBC has said that Bodyguard is the most successful new British TV drama in a decade, a series boosted by the millions of people who were watching it on iPlayer.

At least 10.4 million people in Britain watched the first episode of the drama in the week it was broadcast, according to official figures that show how British TV viewing habits are changing.

An initial audience of 6.8 million tuned in to BBC1 on Sunday 26 August for the first episode of the drama, written by Jed Mercurio, which stars Keeley Hawes as a home secretary and Richard Madden as her close protection officer.

However, the total audience rose by more than 50% when people watching on iPlayer, time-shifted viewing or via set-top box recordings were taken into account.

The audience for the show could be higher still, because official, combined, BARB figures – the UK television audience survey based on monitoring viewing habits of about 5,000 households – only count catch-up viewing through television sets. The BBC said there had been 3m requests on iPlayer for the drama’s first episode, many of which could relate to laptop and mobile phone use not captured by BARB figures.

Overnight viewing figures have been the bedrock of the TV industry for decades but the figures show the enormous influence of catch-up services, where a high-profile launch on a traditional TV station can lead to heavy catch-up viewing throughout the following week.

The broadcaster also pointed to Bodyguard’s strong performance with the “hard-to-reach” 16-34-year-old demographic; 1.2 million of them watched the first episode, which, the BBC claimed, made it the biggest non-soap drama of the year for this age group.

ITV will be hoping that Vanity Fair, its big autumn drama which is going head-to-head with Bodyguard in the Sunday 9pm slot, will also benefit from an uplift in catch-up viewing via the ITV Hub service. Its first episode reached a comparatively small 2.9 million audience, which included those watching on ITV+1.