Secrets from the Clink, TV review: Intriguing exposé of criminal past of celebrities' ancestors

Inside information: Mariella Frostrup discovered more about her great-great-grandfather's incarceration in HMP Lancaster Castle in ‘Secrets from the Clink’

In a more innocent age, the very notion of a celebrity being in jail was enough to trigger hysteria. Phil Spector! Pete Doherty! Paris Hilton!

But now that the D-wing of Pentonville resembles a grim Celebrity Squares reunion special, it's not so unusual.

So, naturally, when I got to Wednesday on my dog-eared copy of the Radio Times and looked at the shows I'd Stabilo Bossed, I had assumed that Secrets from the Clink (ITV), featuring Johnny Vegas, Mariella Frostrup and Len Goodman, would involve the celebs being bunged into a prison for the evening to see how they coped.

Tasteless, yes, but an obvious stop on the continuum of crass celebrity television, which peaked in 2004 with Rebecca Loos getting caught in flagrante delicto with a Gloucester Old Spot. Alas, it wasn't quite "Celebs Do Time".

What the two-part Secrets from the Clink actually did was take Goodman and company and conduct the penal version of Who Do You Think You Are?. This was a history of the malevolent world of 19th-century justice, the story of Victorian prisons told, ably, through the stories of ancestors of The Observer's agony aunt and Moz from Ideal.

Of course, this being ITV, no work of non-fiction could exist without a B/C-list tour guide ("Dr Hilary Jones's Meiji Restoration-era Japan"; "Around the World in 40 Bodegas with Dawn French" – you know the thing). It'd be a bit churlish to complain too much about that though – show a history of Victorian prisons at 9pm and you're basically BBC4 (not that there's anything wrong with that).

But what was intriguing – and unseen here –was the process that the show's producers and researchers must have gone through to find a relevant mob of celebs. An open call to the nation's talent agents asking if any of their clients had 19th-century wrong 'uns in their genealogy? Any larcenists in your family, Terry Wogan?

Or were they just using the genealogical leg work from other sources (Len, for one, has already been on the decidedly similar Who Do You Think You Are?, which is produced by Wall to Wall, the same people who made, you guessed it, Secrets of the Clink.)

By the sounds of things, the Victorian justice system was so sweeping in its nature that the odds were that anyone not descended from Dukedom may well have an ancestor who did bird.

Len's ancestor Henry Blackhall found himself doing hard labour at Portland prison for attacking his own father with a pick-axe, but even he – "obviously a hooligan," according to Len – was overpunished by the institutionalised abuse of the prisons: breaking rocks in the hot sun; turning a weighted handle called a crank, which was tightened by wardens (leading to the warm sobriquet "screw").

The tale of Frostrup's great-great-grandfather William Martin Eckersley – thrown into Lancaster Castle prison for fraud despite being incapacitated by a stroke – was brutal and sad, though had a happy-ish ending. But it was Johnny Vegas – a comic who's made a career from playing up his boozing – who was most moved. His ancestor was Ann Haines, a notorious lush who was jailed more than 100 times for public drunkenness.

A clearly troubled, widowed woman, Haines was destroyed by Victorian "justice" (though her daughter eventually escaped to respectability in St Helens via Leeds). Vegas looked as emotional as we've seen him since his tribute to Paul Whitehouse at last year's comedy awards.

Next week, it's Daisy McAndrew and Michelle Collins. Hold on to your leather prison-issue hats.