Alex Jennings: I owe Dame Maggie Smith for Lady In The Van role

The pair, who previously worked together on stage, were reunited for Nicholas Hytner’s drama, adapted by Alan Bennett from his 1999 West End play of the same name.

“I feel very fortunate that I’ve had two opportunities to work with Maggie, who I think is the best there is, really,” the actor said.

“The first time was in The Importance Of Being Earnest on stage and I’m grown up enough to know that it’s because of her that I’m in this film, that she said she’ll do it with Alex because we have a friendship and a history.”

Alex has only praise for Dame Maggie, who plays Mary Shepherd, an eccentric woman who lived in a battered van on Alan’s driveway for 15 years.

He said: “She makes you want to be better, to up your game, and I feel enormously privileged to be there witnessing what she was creating.”

Alex, who portrays Alan in the movie, said the pair shared some funny moments on set.

“I did crack up. There’s a fantastic moment when Alan was saying goodbye to his mum so I’m popping her into the cab,” he recalled.

“Maggie, as Miss Shepherd, just inserted herself next to me, which I didn’t know was going to happen, to watch the cab leaving. (It’s) brilliant, gorgeous little moments that she’s constantly creating and totally on it script-wise.”

Having portrayed the playwright before on stage, Alex said it is still “weird” to play him on screen, particularly since they are friends.

“It’s kind of weird because I know Alan and have known him for over 25 years. I have his approval, I suppose, so that gives me confidence to get my Alan Bennett going,” he explained.

“Here, I play two Alans and we talk to each other so the whole technical aspect of that was fantastically rewarding. That was a real pleasure to do that.”

The Lady In The Van is in cinemas now.