Conversations from a Long Marriage creator reveals how Joanna Lumley and Roger Allam were cast

"Come on!" I’d shout at my radio and TV. "Where are my contemporaries? The strong, smart, funny women who have laughed and loved their way through life, since the Summer of Love and might still be married to the sexy hippie they met at Glastonbury 71?"

We may be Senior Railcard Holders but we turn up the car radio, sing along with Marvin Gaye and are still dancing in the street with Martha Reeves and the Vandellas.

Yet we were nowhere represented. So I wrote a series myself, about a woman who I recognised, had my references. I placed her in a long marriage that still fizzed with passion for life, music, wine and yes, sex - and I knew who I wanted to play her.

Joanna Lumley epitomised how we all want to grow older. Not just beautiful but engaged, curious, warm, clever and funny. Thank god she said yes, because I didn’t have a back-up choice!

I asked her who she wanted as her husband – and held my breath. Joanna said, "All my friends want to be married to Roger Allam."

Hurrah! My choice too! And the Dream Team was born – dazzling actors, with two of the best voices in broadcasting.

In 2017, we recorded a pilot episode and when I first saw those two at the microphone, I couldn’t stop smiling. I have a schoolgirl crush on them both. Their chemistry was obvious, they genuinely like each other. There is much banter, flirting and laughter in the studio – and that’s before we even start – but the calm and confident skills of our producer, Claire Jones, miraculously manages to pull it all together.

I always planned Conversations From A Long Marriage as a two hander, about a couple talking, when no-one else can hear. There are the occasional one-sided phone chats but no other characters and definitely no neighbours bursting in, uninvited.

It’s sometimes mundane, as they bicker about the bins, dishwasher loading and the etiquette of waving goodbye at the front door but scattered through the 18 episodes of the three series so far, we learn their history. A tragic miscarriage, soon after they met, has left them childless, they have each taken detours off the marital motorway – split up, come back together and even now, there are jealousies and dramas which fuel the passion and the humour.

I’ve been writing comedy for over 35 years – and I have Radio Times to thank for launching my career. My husband, Gavin Petrie and I, both journalists, submitted a script to the Radio Times ‘Sounds Funny’ competition in 1987. The judges were Victoria Wood, Prunella Scales and Douglas Adams (creator of Hitchhiker’s Guide to the Galaxy). We won! The prize was £2,000, which we spent on a stair-carpet and a juice extractor. As Gavin was then Features Editor of RT’s rival TV Times, it provided a lot of merriment. It led to our first (fairly autobiographical) comedy series, Second Thoughts, on Radio 4, starring Lynda Bellingham and James Bolam as a couple trying to keep the magic alive, while living with her two teenagers. The series transferred to ITV for 5 years and was followed by Faith In The Future, again starring Lynda Bellingham – now a divorcee - living with her daughter, Julia Sawalha. This won a British Comedy Award.

Gavin and I have written many more radio and TV series, including Next of Kin, for BBC Television, starring Penelope Keith and William Gaunt as grandparents bringing up orphaned grandchildren and although I wrote Conversations from a Long Marriage on my own, I asked Gavin’s opinion, "What do you think is the secret of a long, happy marriage?"

He answered swiftly, "You tell me and I’ll agree". That made me laugh – which is probably why we’re still together.

As one listener said, "It’s wonderful to be the target audience for a change. We get all the references and it features an older couple enjoying each other – and enjoying sex."

I’m thrilled at the ecstatic reception to Conversations from both critics and listeners and if I’ve learned one very important thing, after four years working together it’s that when a photo is being taken, never, ever stand next to Joanna Lumley.

Joanna Lumley explains why she said "yes" to being married to Roger Allam in Conversations from a Long Marriage

You can’t do anything without good writing. As soon as I read the first script I thought: This is the one. I said "Yes!" because of the writing … and Roger Allam.

I love playing Her (they have no names) but we are not identical. She is scattier than I am, and nosier. What is very wonderful is Jan’s uncanny ability to mimic speech patterns, so it is easy-peasy for me to speak her lines as though they had just that second flowed from my head. I love Her, though: and love being Her.

Roger Allam plays my husband. I am his servant: I think the world of him. Now that we perform from iPads and not scripts, I rather miss the intimate routine of sharing page-turning we had devised. The brilliance of the writing makes it easy to play off each other, to love each other, to have spats and jealousies and reconciliations. He is a wizard and very dry and droll.

People really love Conversations: they tune in to each episode faithfully, and wait eagerly for the next batch, and I have never encountered that before with radio. A woman told me that while doing a long and tedious manual job she had listened to the entire first two series. Everyone who hears them seems to be enchanted by them.

What people say most to me is: Has Jan Etherington got some sort of spy network listening in to our marital conversations? They all feel so real and fresh and relevant and - grim word alert- accessible. Jan has the eyes of a hawk, the ears of a bat and the pen of an angel. I want them to be forever in the mind’s eye, i.e on the radio, where we can imagine everything; the two of them, and what they look like, and how their house is furnished…. Television removes all possible doubt and conjecture, and in any case, we might disappoint (me, not Allam: Allam never disappoints)!

I like to think of listeners - with a gin and tonic, or ironing, or ironing with a gin and tonic - tuning in to hear us at 6:30pm.

Roger Allam reveals he's worried that his "wife" has now become a Dame!

Conversations is very funny and made me laugh. It also meant the opportunity to work with Joanna, which I’d never done before. I love doing radio and don’t get so much opportunity to these days.

Do I empathise with my character? A man whose mind makes appointments that his body can no longer keep? Oh, I understand his pain. A man who is constantly trying to impress his fascinating and beauteous wife? Tell me about it.

Being ‘married’ to Joanna has absolutely has been the perfect partnership and a complete joy thus far, but I’m fearful that now she’s been made a Duchess - or whatever – that we’ll have to record the next series in a throne room and I’ll be expected to bow and scrape and walk backwards in her presence. Luckily I have some very good kneepads.

It’s absolutely great that we have had such a very good response from the listeners and the critics - it means we can make more.

Conversations from a Long Marriage can be streamed now on BBC Sounds. Visit our TV Guide to see what’s on tonight.

This feature originally appeared in the Radio Times magazine. For the biggest interviews and the best TV listings subscribe to Radio Times now and never miss a copy.