Tom Courtenay says working on Grandpa's Great Escape has made him interested in finding out more about the history of the Spitfire.

What do you think it is about David Walliams's works that resonate with a family audience?

It goes from young to old - Kit, who plays my grandson, is 13 and I'm 80, so there's a lovely age span. It's very imaginative and fanciful treatment of a serious subject. The range of it from farcical to lyrical and very tender is rather unusual.

Did you do research into your role?

I took some inspiration from Pauline Collins' role in Quartet. I also know many families who have been touched by Alzheimer's - it's increasingly difficult these days to find someone who hasn't been affected by it in some way.

I wasn't so interested in the history of the Spitfire before getting involved in Grandpa's Great Escape. But upon doing further research and hearing what the old boys had to say about it, I became very engrossed in finding out more about the design and creation of it. Sadly, I'm not sure the creator ever lived to see the success of it. But I find it quite poignant when Grandpa says "there's never been an aeroplane quite like it" because he's absolutely right.

Grandpa is an incredibly resilient character - have you enjoyed playing him? Do you see any similarities between you and him?

We have the same voice and he's about as tall as I am. He's got a nice moustache that I don't normally have, though! I had to do my best to imagine what it may be like to live with Alzheimer's.

The thing I've enjoyed researching is the Spitfires, and trying to make it look as though I feasibly could have been a Spitfire pilot. And I've been enjoying listening to the stories of the Spitfire pilots and have been very touched to hear about the role they played in the war. It was the most manoeuvrable fighter plane at that time and it held the enemy at bay. It didn't win anything, but it encouraged a stand-off which was absolutely crucial.

In terms of characteristics, Grandpa's a bit self-absorbed - which is quite like me!

I don't have any grandchildren of my own but I worked with Kit earlier in the year, and became very fond of him. So when I got on board for Grandpa's Great Escape, I suggested him to the director to play Jack. And thankfully, when the director saw him, he was entranced by him. I was very pleased when he was cast - I liked the serendipity of it and working with young Kit has really made this for me. Because Grandpa has three great loves in his life - the first was his wife, who has sadly passed away, the second is his grandson and the third is his Spitfire.

Do you and your family get together to watch TV over the Christmas period? Do you have any programmes that you always make sure you tune into?

It varies for me - it depends who is in town, and who comes over. It's mostly just Isobel and me - but we do always have the television on whilst we're eating and drinking. I've been friends with David [Walliams] for a while now, so I always make sure to tune into his programmes. And I often find myself hoping for an interesting film.