Tell us about Len...

Len Spud is a disgruntled worker in a toilet roll factory. One weekend he's inspired to make a new toilet paper that hasn't been seen by anyone before. It's the BumFresh range, moist on one side and dry on the other. It's a global hit, and he's a billionaire. I think he only gets a penny a roll, but there's a lot of demand! Then he is up and running with his new money and he doesn't know what to do with it, so he just buys and buys and buys.

It's a cautionary tale that money doesn't really bring you happiness, and that's the bottom line. I know people with a lot of money who seem to be lacking some spirituality in their lives, a kind of inner peace.

Is it something your keen to show your daughters?

I try to instil the value of money and to get them to do a few jobs for pocket money. Especially the eldest, she's nearly 13 now, so sometimes she'll say, "I want to go to the Trafford Centre shopping" and I'll say, "Yes there might be a few bits you can do for me around the house!" The little one, it's hard, she's only five!

Do they like the books?

Olivia has read them all. She is a big fan which was great and when I told her she couldn't believe it. I've read Gangsta Granny. I didn't read Billionaire Boy but then I read the script. He is good, David.

How is Len's relationship with his son?

The bond between Len and his son Joe is a lot stronger when their life is simple. Their relationship begins to drift when Joe starts living in a fantasy world, where he thinks he can have anything he wants; while Joe sees that money can't buy friends or happiness - or their relationship.

Warwick steps in where Len's moral compass fails - he is a bit of a surrogate dad to Joe. Len is quite selfish and is more interested in wooing his new model girlfriend Sapphire than worrying too much about his son's life. He puts Joe in the most expensive school, despite the fact that it might not necessarily suit Joe.

This is Elliot Sprakes's first really big telly role, what was it like working with someone who was so young?

At first Elliot was very shy in early rehearsals. It must be very daunting for him but when he read the script he came alive. He's very natural and that's what you want - truth, believability and a natural side to it. When it comes down to doing the job in hand I didn't see him struggling, I've not had to take him under my wing, but I always check in with him and see if he's alright.

When you read the script first did you laugh a lot?

I did - it's funny, but there's also quite a lot of emotion. When Joe goes missing there's a press conference where I'm really upset - I don't know where he is and I've lost everything. I had to go in at the deep end with the more tragic side of it, but then we started having fun. A lot of the scenes with Catherine [Tate] were great fun - she plays Sapphire Diamond, who is a complete gold digger.

Have you worked with David Walliams before?

We worked together on You Are Here, which started as a sketch show. The cast included Keith Allen, Matt Lucas, David and me. It was about a weird little town called Here. I was a ginger dad with very thick curly hair who had an identical son played by Alfie Allen, who is now in Game Of Thrones.

I'm a fan of David's work and of Catherine's. I've worked with Warwick on The Fast Show before and we did a parody. He also directed Snow White and the Seven Dwarfs at Manchester Opera House last year which my daughter Olivia was in. So when I picked her up I would see Warwick at stage door. It's a great cast.

What's Christmas like in your house?

I love Christmas, I am a big fan. We do all the traditional things, Christmas dinner, the presents on Christmas morning, Santa's been and all that kind of thing. I think you follow what your parents did and my mum and dad were very traditional.

Do you watch telly as a family?

Not as much, one thing I used to absolutely crave was the TV Times or The Radio Times at Christmas to see the films. The first thing you would do was leap to the film pages to see what had just been released on TV, but films are more accessible now. I am a massive Bond fan, it used to be the Queen's Speech and then a Bond film!