What drew you to this project?

The answer is simple: Dick Clement and Ian La Frenais. They're simply legendary writers. I've loved them since growing up with their classic sitcoms, Porridge and The Likely Lads. The craft that goes into their work is wonderful. The structure of their lines is very satisfying. It really helps you with your timing. I get very excited when something new comes along from writers of that quality. It's been a while since they've come up with a new idea for British TV, so it's thrilling to be involved with this. In the current climate of constant remakes and reruns, any new sitcom is very appealing, but one by Dick and Ian is even better.

Were you nervous when you met Dick and Ian?

No, because I knew I'd already got the job and that they had already approved my casting! I was very pleased to meet them. And when I heard them laughing at my performance, I felt relief and satisfaction. You could tell they were happy to hear my interpretation of their work.

How would you describe Henry IX?

He could be King, he could be anybody, but he's essentially trapped, like many of us may be. It's not to do with the life you're leading, it's to do with how you're feeling within yourself. It's not to do with the people you're with or your job, it's to do with how you feel about yourself at night, when everyone else is asleep. His wife doesn't understand. They have an argument, and she tells him to find satisfaction inside himself!

But does the fact that he is the King exacerbate his sense of dissatisfaction?

Yes. It adds joy to the idea because he is someone who is told what to do every minute of the day. He is never allowed to make his own decisions. After 25 years of service, he's had enough. He says, "I deserve a different life. I want to lead my own life now. I really don't want to be treated like a baby any more. I want to be able to put on my own socks!" In that regard, being King does add to his midlife crisis, but essentially it could be happening to anybody. Henry wants to break free of routine and repetition and dead-end-ness. Being King is a dead end. Your whole life is prescribed for you. Things are even in place for your death. So he is asking himself, "Can I take control of my own destiny?"

Is the series at all a comment on the real-life Royal Family?

No. It is not referring to the current Royal family. It's Britain now, in 2017, but it has nothing to do with reality - it's a totally fictitious family. There is a Scandinavian queen on the throne. That's great because it's something completely new. It's not imitation or an echo of real life. If people try to read something into it, it will quickly become apparent that it is fruitless exercise. There is nothing that refers to it any way, other than the status of the family.

Have you done a lot of research into royal etiquette?

I don't want to get too bogged down with all that stuff because it's more fun to play around with it in our imaginary world. A friend went to The Audience, the play about the Queen, and she was sitting next to a minor Royal. Every time there was an etiquette faux pas on stage, the minor Royal would tut. We can expect a lot of tutting!

Have you enjoyed working with Sally?

The whole cast is amazing. When I saw the line-up, I thought, "Oh my God!" I have loved working with Sally. We have very similar timing. We are shaping it to our own ends. We like to play with it and I think we match each other very well. We instantly hit it off and do a lot of giggling.

What do you hope viewers will take away from watching Henry IX?

I hope it's a real treat for people to have a show written by these legendary writers. It's a very big deal. I hope they will find it moving because there's a lot that's very human and touching about family relationships. But above all, I hope people will laugh! I think they will.