Derek Jacobi was excellent in Last Tango In Halifax (BBC One, Tuesday, 9pm) but as with all well-known actors, you can sometimes see their most famous role squirming and wriggling just below the skin, like the alien in John Hurt's stomach, ready to break through at any moment.

In Sir Derek's case, the breakthrough happened about half way into Last Tango's first episode when Alan Buttershaw, his character, started stuttering. "Ha-ha-ha-ha-ha-hallo," he said, and there he was, after all these years: Tiberius Claudius Drusus Nero Germanicus This-That-And-The-Other, known to his friends as Claudius the Stammerer or Clau-Clau-Claudius.

Sir Derek may not have intended any of this, but it was useful to be reminded of Claudius in this way. It's still Jacobi's most acclaimed role but it also sentenced him to a career of shouting in the evenings and slightly arch film and TV roles. He deserves more range and in Last Tango was given it in the role of a couthy Yorkshireman, all dishevelled and cosy and wrinkled.

Wrinkled. There's a surprise. We don't often see elderly characters in drama, unless it's as comedy relief or grotesquerie. It's as if TV producers are repulsed by ageing (society certainly is) but with Last Tango, we might at last be seeing a change and an acknowledgement that there's an appetite for portraying the lives of the elderly in a realistic and meaningful way.

Last Tango also made a good stab at showing the lives of the middle classes – another group forgotten in the Downtown-Shameless pincer movement.

Jacobi's character was reigniting his love affair with Celia Dawson (Anne Reid) and their daughters were good examples of what the middle classes have become: all cracked and broken, always arguing in kitchens and cars and trying to hide it under the old assurances of children and houses and work. This group just hasn't been on TV much and, like the elderly, it's time they were welcomed back.

Aside from all this, Last Tango In Halifax was just a solid, good, funny drama. Jacobi and Reid's characters were particularly good together: contemplative, amusing, sharp and willing to talk honestly about spending a long time in unfulfilling marriages. "I feel like I've been on my own for 40 years," said Celia. I wonder how many other seemingly happy elderly people feel that way?

The other big theme of the programme – although it was nudged subtly towards us rather than shoved in our faces – was regret. We found out, for example, that the couple hadn't spoken since 1953 when a note Celia sent with her new address never got to Alan. He then spent 60 years thinking he'd been stood up while she thought he hadn't wanted to get in touch.

The way both of them slowly, gently, realised the truth was played beautifully by Reid and Jacobi, and then there was all the nervousness and fussiness of preparing for a first date again. Shouldn't we learn to deal with all that by the time we're in our 60s and 70s? Derek Jacobi looked out of a window and saw a teenage boy who'd been stood up and we realised: no, we don't learn that. We're just the same as we've always been.