Like most of us I love a good TV drama, which is why I sat down to watch both The City and the City and Deep State recently. But this time irritation spoiled my enjoyment. The lead actors of both British series, in their middle 50s, were cast against female lead actors as romantic partners, both in their 30s.

Once you see this, it’s hard to unsee it. So I reflected on other forms of entertainment. Saturday-night TV gave me a range of shows with men in middle age, and older; and female co-presenters who weren’t, or who certainly looked like they weren’t, much older than 35. Or take film: I love to watch Tom Cruise, but the really impossible mission seems to be to star with a female actor his own age. The latest Mission Impossible film sees the 55-year-old paired with 34-year-old Rebecca Ferguson, which sends a message to me that men in middle age are still capable and vibrant, energetic and passionate, whereas middle-aged women are redundant.

In a sample of 12 cinema releases this month, there are nine lead actresses in the 19-to-30 age range, but only three films with female leads over the age of 40. Their male co-stars aren’t bound by this formula. Why is it that our middle-aged male screen heroes seem unable to contemplate a relationship with a woman of their own age?

I’m 51 and my husband is 49. All our friends are similar ages and with similarly aged partners. But in the world of TV, middle-aged women like me are often absent. On TV, if you’re a woman every year over 40 seems to count for five years.

Two years ago, I set myself a challenge: to relaunch my acting career, which I’d shelved very early on for my parental and filial caring responsibilities, looking after two daughters with disabilities and a mother diagnosed with Alzheimer’s. Two decades on, I had no idea how difficult this second attempt as a performer would prove to be, but in an industry dominated by youth – and where old for women is 35 – the ageism is shockingly blatant.

So today, with the recent words of the actor Frances McDormand about the inclusivity rider on film contracts featuring prominently in my thoughts, I am launching a new campaign: Acting Your Age . I’m calling on writers, commissioners, directors and performers to embrace a generation of invisible women.

I don’t want the wonderful Sarah Lancashire, star of Happy Valley, to be the only exception to a British rule – or for the age-appropriate casting of Olivia Colman in The Crown to be a rarity. I don’t want Reese Witherspoon and Nicole Kidman to have to fight tooth and nail to get a series such as Big Little Lies made. I want these to be the normal way of things for middle-aged women, just as they are for middle-aged men.

Of course, the marginalisation of middle-aged women is not limited to acting – as the deputy governor of the Bank of England, Ben Broadbent, showed this week when he referred to a “menopausal economy”, older women are portrayed negatively in all walks of life. But perhaps if we achieved visibility on the influencers that are TV and film, we might be deemed to exist across the board. Isn’t it time to end the notion that the advent of a woman’s wrinkles and grey hair means she can no longer pay her mortgage through acting?

• Nicola Clark is a writer, campaigner and performer