David Warner admits that he hasn't exactly cornered the market in humorous roles. He's famous, instead, for playing dark and troubled men - the photographer who loses his head, literally, in The Omen, the evil German SS General Reinhardt Heydrich in Holocaust and, more recently, the senile father, Povel, in the detective series, Wallander. "So, none of it a barrel of laughs," he smiles.

It was unlikely casting, then, when he was approached to play the role of Frank in Albert's Memorial. "I couldn't believe my luck," he says. "But I was delighted to be able to show a side of myself that audiences won't have seen. I saw it as an opportunity for humour. At last."

During his long career, the veteran Shakespearean actor has appeared on both stage and screen and has more than 100 movie roles to his name. "From experience, I'd say that you often find that the more serious a project is on screen, the more laughter you get when the camera stops rolling. It's a kind of gallows humour. I wondered, then, if the reverse would be true when it came to filming a gentle comedy like Albert's Memorial. Would everyone be miserable as sin, off screen? But I'm happy to say that when it came to working with Sir David, I haven't had as much fun as when I worked with Gregory Peck on The Omen - and, believe it or not, I had the best time ever on that movie. Just like Gregory Peck, I discovered that Sir David had a terrific sense of humour and that we tended to laugh at exactly the same things. There was a lot of mutual ribbing about who was the poshest - Sir David, a knight of the realm, who has received a tap on the shoulder from the Queen, or me, a Shakespearean actor."

"Myself and Michael Jayston, who plays the dying Albert, were old friends in real life from our days at Stratford. On one occasion I'd played Hamlet and he'd played Laertes. So the pair of us, actually, had the mickey taken out of us," he smiles. "Quite honestly, there were many times during filming when the make up ladies had to be called in to wipe away tears of laughter. And that is always a very good sign on a set."

The humour, of course, persists on screen, too, although this time the laughs come from the constant bickering between the two central characters, Frank and Harry. "Frank is amusing, not because he's always telling jokes, but because of the way that he plays off David's character. Harry is one of life's enthusiasts. He chirrups and chatters and wheels and deals. Frank, on the other hand is brusque and glum and given to sarcasm. Physically too, of course, they're totally different. Frank is lanky, Harry short. The laughs come from the differences in both their physicality and their personalities."

The characters two extremes are counterbalanced by Vicki - the mysterious, beautiful, young German woman who joins them on their journey as they motor through France and Germany, with their comrade in a coffin on the roof rack. "And working with Judith Hoersch, who plays the character was also a real pleasure," he says. "I always have so much admiration for any actor who can work fluently in a foreign language. If you asked me to work in French or German, I'd be lost!' he admits.

David hopes the drama will appeal across the age divide. "That includes young people too, and not just because having Judith in the drama means they're also represented in some way. In addition, there is also the story - told in flashbacks - of the three old codgers, when they were young men, fighting in the Second World War. What happened to them, explains why they are drawn back to this particular place in Germany and why Albert has asked to be buried there. The full story, which is actually rather shocking, is not revealed until the end."

By the time the drama ends, David hopes the audience will have come along on the journey, for the simple joy of it. "First and foremost we made it as a little black comedy that would entertain, but at the same time, even though we never intended it as history lesson, the viewers may also learn something along the way. After all," he says, "as the story unfolds, it does illuminate some of the shocking events of the Second World War and it does, I hope, honour those who fought for us. Without them we wouldn't have the kind of life and the freedoms that we all enjoy today."

Those alive at the time", he says, "need no reminding. I was born in 1941, so I was a baby during the war itself, but in those post war years, you were brought up in a kind of austerity. Rationing, for example, meant that I didn't taste my first banana until I was goodness knows what age. These days, even when minor things go wrong, everyone complains, but people who'd lived through the Blitz seemed to have more perspective and they certainly never forgot the price that had been paid for victory. I'm not at all sure now, though, that teenagers, for example, really understand the debt that we owe those who fought. For the most part, if you ask them to tell you about Churchill, for example, they'll say, 'He's a dog who sells insurance!" the actor laughs. "Maybe Albert's Memorial will go a little way to changing that."

As the final credits roll he hopes the audience will have enjoyed the ride with Frank, Vicki and Harry. "I hope it will leave people with a smile on their face and, perhaps, a tear in their eye. If so, we'll have done our jobs".

After Albert's Memorial the actor will next be seen in the first episode of the new series of Midsomer Murders. "In production terms John Nettles has left now and this will be the first time we see Neil Dudgeon in the leading role. It's scheduled for sometime next year as there are several films John has recorded still to transmit. And it's great to be included in that. I'll be playing an ageing racing driver, but again, not one of the sick old men that I tend to get offered a lot, these days," he laughs.

He wonders, perhaps, if playing Frank has turned the tide. If not, he says, he'll content himself with having played this role. "What I loved most about Frank is that he's a man who, of course, may have a few health issues. Who doesn't at his age? But he's also vital and bright and quietly subversive. More of those roles please!"