It feels eerily apposite that the beginning of a conversation with Mark Gatiss about the twisted delights of European horror should be drowned out by a constant, violent hammering. Is it a vampire countess being nailed into a coffin? Or an unspeakable act of torture in the basement? It is, in fact, a slab of veal being tenderised in a bijou Italian restaurant in Swiss Cottage, North London.

The writer, actor, novelist and all-round extraordinary gentleman didn’t order the cruel escalope - he had the salmon carbonara - but he’ll be getting through much of the menu over the next five weeks while he stars as King Charles I in Howard Brenton’s new play, 55 Days, at the theatre round the corner.

A lean and sprightly 46, Gatiss is a busy man. He started researching his freestanding 90-minute documentary, Horror Europa, for BBC4 straight after finishing a run in The Recruiting Officer at the Donmar Warehouse in April. He has also been writing BBC1’s beloved Sherlock, which he co-created with Steven Moffat and in which he appears (a third series goes into production in January).

Following on from his unashamedly personal three-part A History of Horror in 2010, Horror Europa catapulted Gatiss on a whistle-stop, ten-day tour of the continent… a working holiday, if you like.

While ocasionally forgetting which country he had woken up in, he interviewed key horror figures - including legendary Italian Dario Argento and powerhouse Guillermo del Toro (yes, he’s from Mexico, but his Devil’s Backbone and Pan’s Labyrinth depict the horror of the Spanish Civil War). And, by visiting their locations, he trod in the footsteps of Germany’s Nosferatu, a Symphony of Horrors and France’s Les Diaboliques, and the more obscure “horror for the package holiday era” Who Can Kill a Child? from Spain.

Horror Europa follows the same remit as A History of Horror – “personal taste woven into a sort of thesis”, as Gatiss describes it. It’s another vital, informed, affectionate document about a genre all too readily dismissed as schlock with low artistic merit.

In the previous series, Gatiss exorcised his boyhood love of the 1930s Universal Studios monsters, and the gory, glory years of our very own Hammer. Horror Europa allows him to explore further flung corners of the generic map, from silent German Expressionism - itself an affirmation of national esteem after First World War humiliation - to the wave of symbolic Gothic horror movies in Spain under the boot of Franco… films like Narciso Ibáñez Serrador’s La Residencia (1969), which Gatiss describes as having “defeat, loss and melancholy” running through them.

The programme wears its cleverness lightly, but it’s bracing stuff, even for horror nerds, among whose number I count myself. Gatiss and I are of a similar vintage: we both grew up besotted by the ghoulish film stills we pored over in compendiums such as Denis Gifford’s A Pictorial History of Horror Movies (“the green one!”) and Alan G Frank’s Horror Movies, a dog-eared copy of which is atop a prop TV in Horror Europa. As we stab at our pasta, a reverie for arcane images of German silents The Cabinet of Dr Caligari (1919), The Golem (1920) and The Student of Prague (1913) takes hold. (Gatiss was dissuaded from using the gag, “Like most things, the Germans started it,” in the programme.)

“One of the reasons those stills are chosen is that they’re f ***ing scary!” Gatiss whoops. “Conrad Veidt from Caligari with the girl draped across his arm? When you actually see the film it’s all jerky, but it doesn’t matter. You’d glimpse that Golem head in House of Hammer magazine, or in these books, and say to yourself, well, I’ll never see that one.”

It’s for the greater cultural good that Gatiss has been allowed to channel his “horror-obsessed youth” into something concrete, with rarely seen clips. Today’s youngsters, with online access to, well, everything, will never know the wonder of unattainability our generation experienced. (But, sadly, his programmes are unlikely to turn up on DVD because to licence those clips would be prohibitively costly.)

“That wonderful line from Inherit the Wind, when Spencer Tracy’s talking about evolution and progress. ‘You can have a telephone but you lose the charm of distance.’ For everything you gain, you do lose something. How marvellous it is that you can now watch what remains of The Golem on YouTube, whereas you used to have to wait for a BBC scheduler to put it on.”

Those same schedulers have honoured Horror Europa with a Halloween week slot, and BBC4’s door is, it seems, open for future geographical excursions - Horror Asia? Horror Latina? Don’t expect an affectionate treatise on modern horror films, though. The Human Centipede - a rare Dutch entry in the canon - gets a quick nod in Europa, but on the whole, Gatiss finds its ilk “disturbing in the wrong way… There’s nothing there, except a sort of numbing repetition.”

He pulls back, for fear of sounding like a curmudgeon. “I was a very bloodthirsty youth,” he admits. “But without any supernatural element, you might just as well stand and watch a car crash.”

The previous Friday, Gatiss watched 1973 British horror And Now the Screaming Starts! “For its time, it’s quite gory,” he says, as we head back to the theatre. “Geoffrey Whitehead with his eyes out? At the time people thought it was repellent and disgraceful, but you look at it now, you think: good on you!”

Horror Europa with Mark Gatiss is on tonight at 9:00pm on BBC4