The sight of Mark Gatiss in costume could be considered almost passé by now.

After all, we’ve recently seen him sporting an impressive hairpiece and beard as Robert Cecil in Gunpowder, not to mention his barely recognisable transformation into the overweight Prince Regent for Tom Hardy’s Taboo earlier this year.

When we meet he’s sporting long flowing auburn hair and a loosely wrapped dressing gown and it’s difficult not to feel slightly creeped out.

Of course, from Sherlock to Doctor Who, Game Of Thrones and many more, Mark is an absolute master of the macabre. 

Today he is revelling in the opportunity to return to one of his earliest skin-crawling character creations – Val Denton from The League Of Gentlemen.

Not only that, but he’s celebrating his 51st birthday and, following a pitch-black scene in the Denton household, he’s presented with a cake by cheering members of the cast and crew. He seems so happy he could burst.

“I am pleased to be filming this on my birthday because it is the sort of thing that I have always liked,” he grins.

“It involves a pentagram.”

Mark isn’t the only one in celebratory mood, either, as The League Of Gentlemen cast reunites to celebrate the show’s 20th anniversary at the BBC with three special episodes over Christmas.

The other performing members of The League – Steve Pemberton and Reece Shearsmith, along with co-creator Jeremy Dyson – are on set and, with the exception of Jeremy, are also in costume.

There are half a dozen toads for the scenes at the home of salientian (amphibian) superfan Harvey Denton and one is, we’re told, currently missing.

Even the garish wallpaper from the original series has been redrawn by computer and specially printed, giving an insight into the care that has gone into the return of one of the most influential turn-of-the-century comedy shows.

Of course, that means there’s a hefty whack of anticipation for the new episodes but Mark insists the team is having a whale of a time.

“It’s great,” he says when asked why they’ve chosen to bring the show back now.

“The lovely thing is that it is born of wanting to do it, not having to do it – like a 90s band going back on the road. So there was a lightness to the whole thing which has helped us a lot in filming.” 

Mark met Steve and Reece in 1986 at Yorkshire’s Bretton Hall College where they bonded over a shared love of Alan Bennett, Victoria Wood and Saturday-night horror films. They were introduced to Jeremy and The League Of Gentlemen was born.

Soon, the four friends took their show on the road, winning the prestigious Perrier Award at the Edinburgh Festival before going on to a BBC Radio 4 series, On The Town With The League Of Gentlemen. This won the Sony Silver Award 20 years ago, which led to a BBC2 pilot and the subsequent first TV series that won a Bafta and a Royal Television Society award and the Rose d’Or in Montreux.

Three series followed, plus a film in 2005, and although the actors went their separate ways, they remained in touch. So while it may be a long time since The League cast was together on screen, Mark says the return to the fictional town of Royston Vasey never felt forced.

“It is a strange thing,” he says.

“I thought it would really take us a couple of days to get back into the swing of it and it didn’t. We haven’t done the Dentons for 17 years and I looked at a few things and thought, ‘I can’t remember – what’s the voice?’ But mostly you just go, ‘I remember this’ and you flow back into it.”

Today they’re shooting interior scenes at Manchester’s Old Granada Studios but they have, of course, returned to film in Hadfield, the Derbyshire town that doubles for Royston Vasey.

And while Mark’s memory of the characters may not have changed, Hadfield certainly has.

“Yes, ironically, Hadfield, where we are shooting, has gone a bit chichi and gentrified. It’s nice,” he smiles.

“It is bigger thanI remember but we have had to dirty it down. 

“Mettricks, the butchers, is still there and it says ‘Voted England’s Best Butcher’. I don’t know who voted for it but that is pretty good. I like to think we had a hand in it.”

He adds the people of Hadfield seem happy to have them back and says this time around there were considerable crowds watching filming.

“Like Sherlock, there were people behind barriers and things that never happened before,” he says.

“They used to throw potatoes at us.

“If you drive through this country there will often be a brown sign saying ‘Lorna Doone country’ or ‘Robin Hood country’. People are desperate for a ‘thing’. So I think it has been great. I am sure there are a few naysayers but mostly it has given it a ‘thing’”.

It is also, Mark continues, a more enjoyable experience than shooting in London.

“London is terribly hard to film in,” he reveals.

“People are aggressive these days, which I find so disappointing, because if anything like that had come near me as a kid we would have been so excited. People are just so grumpy.”

So if Royston Vasey has changed so much, have its residents changed, too? And what on earth would they make of Brexit?

“The people of Royston Vasey are so strange that many of them can’t vote, can’t eat, can’t see,” he says.

“I wouldn’t like to presume the politics of Royston Vasey. Because it is a sketch show it is too diverse. It is a weird bunch of strange people roped together into a concept.”

It is a long way from the early days when it was touch and go as to whether the show would make it to the screen. It was almost cancelled while the gang drove around the country looking for their Royston Vasey – a moment Mark considers pivotal.

“The show was turned down about seven times even though we had won the Perrier and done the radio series to great acclaim,” he says.

“It was one of those sliding-doors moments.”

While the show went on to become a cult favourite, as well as kick-starting the careers of Mark, Steve, Reece and Jeremy, he suggests it might not be given the same chance in the current climate.

“The landscape has changed so much,” Mark says.

“There are still a lot of wonderful risks being taken but it is a very strange show to have been commissioned and to have such success. You can have an incredibly positive experience with one section and a very negative experience with another. It depends on the taste of a commissioner, how bold they are, how much they love you.”

The show’s success is history now and in 18 days they have managed to film three new tales for Christmas. Mark will be watching from his London home and if viewers enjoy the episodes as much as he’s enjoyed making them, we may still be talking about them in 20 years’ time. 

The League Of Gentlemen is on Monday at 10pm on BBC2.