TV star Mark Gatiss has told how he based his Sherlock alter-ego Mycroft on Peter Mandelson.

The actor and writer plays the politician, who was one of the key architects behind New Labour, in new Channel 4 drama Coalition.

But Gatiss said that his depiction of Mycroft - the older brother of Benedict Cumberbatch's detective in the TV series which he co-created with Steven Moffat - was already inspired by Mandelson.

"I based Mycroft on Peter Mandelson. It was explicit even before I was going to play him," the actor told Radio Times magazine.

"Steven... and I talked about how Mandelsonian Mycroft was... Conan Doyle says Mycroft is the British government. He's the power behind the throne."

Gatiss also complained that there was a "massive satire gap" on British TV screens.

"John Cleese said satire is only possible under a really horrible Conservative government, which is what we have.

"There should be some very young people doing blistering satire - especially when you have people like Nigel Farage, who you could easily portray as Zippy, or Mr Toad, which is exactly who he is, come to think of it," he said.

"It would need to be a really vicious satire - and I'm too old."

He said of Coalition, which looks at the formation of the current government: "It's something we're going to be encountering very soon again.

"We'll have a minority Tory or a Labour/SNP government. But the world will be thinking, 'That's not stable.' And business confidence will leach away.

"As a politics junkie it's incredibly exciting, but the next election is also terrifying. It would be horrific if the only time the public don't change their mind on a by-election winning party is with Ukip."