'Doctor Who' spin-off show 'Class' is being lined up for a second series.

The cast of Class

The cast of Class

The highly-anticipated sci-fi programme won't hit television screens until later this week but bosses at the BBC are convinced it'll be a hit and are already toying with the idea of doing another installment.

Katherine Kelly - who will portray physics teacher Miss Quill - accidentally let slip to the Daily Star newspaper: "They're already talking about a second series."

The new drama is set in Coal Hill, the school that previously featured on the main show, which former companion Clara Oswald (Jenna Coleman) recently taught at in Shoreditch, east London.

The academy will be targeted by aliens and The Doctor - played by Peter Capaldi - will arrive in his Tardis to help the children fight off an evil monster called Corikinus.

The programme - a Young Adult series dubbed "the British 'Buffy the Vampire Slayer'- has been penned by YA author Patrick Ness and will consist of eight episodes, each lasting 45 minutes.

Patrick previously said: "I can't wait for people to meet the heroes of 'Class', to meet the all-new villains and aliens, to remember that the horrors of the darkest corners of existence are just about on par with having to pass your A-Levels."

And it's believed the Time Lord's appearance in the first episode won't be his last in the spin-off series as it's thought he'll continue to make cameos along the way.

A source said recently: "It will have a close connection with 'Doctor Who' so don't be surprised if Peter pops up."

Details on the series are being kept closely to producers' chests but it was previously announced that exciting young new talents Greg Austin, Fady Elsayed, Sophie Hopkins and Vivian Oparah will star as sixth form students.

Each of them will have hidden secrets and desires and they must all deal with their own worst fears, navigating a life of friends, parents, school work, sex, sorrow - and possibly the end of existence.

'Class' will hit screens on BBC Three on Thursday (20.10.16).