Unforgotten, ITV

The rule doesn’t always hold good, but in a television drama a fairly reliable kitemark of quality is when the opening credits list the cast and you’ve heard of them. The title sequence of Unforgotten promised Trevor Eve, Nicola Walker, Sanjeev Bhaskar, Tom Courtenay, Gemma Jones, Ruth Sheen, Peter Egan, Hannah Gordon, Bernard Hill, Cherie Lunghi and Tom Cobbleigh. OK not Uncle Tom, but you get the picture.

The premise of Chris Lang’s script – yet another body unearthed after many years, reheating yet another cold case – may sound on first acquaintance as if it could do with more time in the pot. Or even the recycling bin. But while two detectives threw themselves into the business of identifying the body, the rest of the episode introduced several apparently random characters going about their lives at various points of the social spectrum: Courtenay as a husband in a wheelchair caring for his wife with dementia (Jones); Eve as a spivvy self-made squillionaire who is the government’s newly appointed entreneurship tsar; Sheen as a mumsy community do-gooder helping a teenage boy through his GCSEs; and Hill as a pathologically selfless vicar with a controlling streak.

As the episode commuted between these disparate lives, and back and forth to the skeleton dug up in a basement, it felt as if a vastly ambitious state-of-the-nation drama about church, education, health, social mobility and the generation gap had been bolted onto the side of a competent crime drama. The crime drama is actually the light relief, hence presumably the presence of Bhaskar, but also Walker as his boss. She has a malleable face that can flit between grim (Spooks, A View from the Bridge) and jolly. The latter look was on duty here. She even flirts outrageously with the forensics geeks from the lab. “I have absolutely no idea what you’re talking about,” she said to one of them after he’d blinded her with some science, “but I’ve slightly fallen in love with you.” Mutual, Ms Walker, mutual.

The excavated bones, potentially dateable to anything between the Battle of Bosworth and five years ago, turned out – through clever sleuthing and whizzy forensics involving the history of an ancient Morgan Spider – to belong to a man who was possibly murdered (judging by the size of the hole in his skull), back in the 1970s. His diary turned up and – guess what? – contained the names of four people in whose company we have spent the previous hour. So far so intriguing.

• Unforgotten Series 2 reviewed on theartsdesk