Sitcom veteran Marcia Warren plays Penelope...

Please run through your character's traits for us...

She's either taken one beta-blocker too many or she has narcolepsy or she is dim-witted in the most charming way. I think it's the beta-blockers because she has good and bad days. Only by episode six does she realise that Freddie and Stuart are a couple!

She never really knows where she is. In one scene in a nightclub, she asks, "Have you changed the furniture in your flat? It's very nice". She thinks she's still at Freddie and Stuart's.

What is her relationship with Freddie and Stuart like?

They been through everything together over the last 50 years, but unfortunately she's forgotten most of it! She doesn't really like going to their flat. She doesn't like the insults even though they come from a loving place. She's too sensitive. But the funny thing is, she says the most outrageous things herself.

Please outline the experience of working with Ian and Derek...

It's been wonderful. I had worked with Ian before. We toured Europe together in Hamlet. I played his mother - but I was only a baby! That was 35 years ago - I had never envisaged working with Ian again. Both Ian and Derek are great classical actors, so it's a marvellous base for working properly on a sitcom. They dig really deep and produce these wonderful performances. Their timing is marvellous. They are able to pause to take in the audience's laughter because they've done so much stage work. Acting in the theatre for so many years counts for a lot.

Have enjoyed working with writer Gary Janetti?

Absolutely. He's brilliant. He's totally in charge of everything from costume and hair to the script. He's a show-runner, and I don't mean a runner who makes the tea! He's fantastic at working off-the-cuff. During a recording, he will come onto the floor and give us new lines. One night, we all went into a huddle in front of the audience and he said, "We're changing this bit." It's quite scary, but really exciting.

Have you been well looked after on this show?

Absolutely. We have got two knights on the show, and we've all been treated fantastically. I said to the producer, "Would you have treated us this well if they were only CBEs?" And he said, "Of course!"

Have you enjoyed working in front of a studio audience?

Yes. You can get a bit stale if you rehearse too much. Comedy becomes more serious the longer you rehearse it. But then to perform in front of a studio audience and get gales of laughter is marvellous. I remember watching the first scene of the show from the green room. There was incredible excitement in the audience. As soon as Ian and Derek spoke, there were great roars of laughter. It was a magical evening. All in all, this job has been the most fabulous experience.