You bring up an interesting point for sure.
The romance between Celia and Alan on Last Tango in Halifax was inspired by Sally Wainwright’s mother’s second marriage and love rediscovered late in life through a UK social media website, and about how those two inspired those around them. Sally Wainwright said in an interview she watched her own mother become more passionate, emotional, and animated with life and Sally wanted to inspire others with her story (with her mother’s blessing). It’s true Sally Wainwright brought in drama, adventure, and two dysfunctional families for added contrast. I think Sally Wainwright does drama well – she also did the series Scott & Bailey (another big favourite of mine) and Happy Valley (which I haven’t seen yet). It’s remarkable in TV that the three female leads are all over the age of 40, and as with Scott & Bailey they’re strong female roles and not merely a lead male’s wife, mistress, mother, or girlfriend, but fully developed characters in their own right.
I especially like the honest dialogue. I heard later several of the scenes including conversations between Celia and Caroline were based on real situations that happened, and I wasn’t surprised because they were so real and honest (one example being Caroline’s discomfort at her mother enthusiastically talking about her sex life). The show does away with TV ageist stereotypes and IMO the added contrasting drama is nice because it’s unpredictable and not boring.
I love the 4 actors featured who all do an outstanding job: Derek Jacobi (I Claudius, Vicious) plays Alan, Anne Reid is Celia (hard to believe she’s 81 now!), and their daughters played by Sarah Lancashire who has long been a favourite British actress of mine, and Nicola Walker. The series won critical acclaim and the BAFTA TV award for best drama series. I expected a nice, warm, fuzzy love story and was pleasantly surprised it turned out to be more. It's a romantic drama.
For anyone who hasn’t seen it, like others here I recommend Sally Wainwright’s Scott & Bailey (set in Manchester), especially the first 4 of the 5 seasons – it’s much more than just a regular police drama series. It’s another example of surprisingly meaty roles for female leads and I like how the series explores those characters in depth and not just the crime scenes they encounter.
I heard Diane Keaton has acquired the rights to Last Tango for a US TV remake. I suspect much of the original charm will be lost but I could be proven wrong. An Americanized Doc Martin remake will also be coming to TV.