Researchers have calculated a formula for the perfect TV episode – and found Downton Abbey consistently comes closest to the ideal.

Although the last episode of Friends was voted top by the public, followed by Eastenders: Christmas Day 2007, analysts found Downton was scientifically superior.

Studying the 50 most popular shows of the past decade, experts at Bournemouth University's Media School found the best recipe for an episode was 65 percent drama, 12 percent shocks, nine percent comedy, eight percent action and six percent romance.

TV expert Boyd Hilton and analysts at Bournemouth University's Media School carried out painstaking research and found Downton Abbey season three, episode five - where Sybil dies, came closest to this.

It contained 36 minutes of 'drama', 3 mins 10 seconds of shock and surprise, 1 minute 10 seconds of comedy, 3 mins 10 seconds of action and 2 minutes 50 seconds of romance.

That equates to 78 percent drama, seven percent shocks and surprises, two percent comedy, seven percent action and six percent romance.

The study, commissioned by BT TV, found Desperate Housewives: Bang season three, episode seven was the most action-packed with 33 percent action.

Meanwhile, Modern Family: Hawaii season one, episode 23 was the funniest, consisting of 74 percent comedy.

The Friends episode which topped the poll of 2,000 Brits, was made up of 48 percent drama, 29 percent comedy, two percent romance and 21 percent shocks and surprises.

TV reviewer Boyd Hilton said: 'What makes this research so exciting and unique is how it helps us work out why a particular episode is so powerful and unmissable.

'This is the ultimate guide to the recipe for TV Gold.'

Delia Bushell, Head of BT TV, said: 'The small screen now rivals the big screen thanks to the huge number of gripping TV series, unmissable sport and box office hits available at our fingertips.

'As we launch the next exciting phase of BT TV we wanted to know what makes TV so unmissable. Through our research, we've cracked the code.'

The most dramatic episode was found to be The Walking Dead: No Sanctuary (Season five, episode one) - 98 percent drama.

There was a tie for most shocking between Grey's Anatomy: Sanctuary season six, episode 23 and Dexter: Seeing Red season one, episode 10 - both with 23 percent of shocks and surprises.

Meanwhile, the most romantic was deemed to be Sex and the City: An American Girl in Paris: Part Deux season six, episode 20 with 28 percent romance.