Casting is crucial in a TV drama. Get the casting wrong and the whole house of cards comes tumbling down. Casting was the reason Rebus starring fresh-faced John Hannah didn't work, but Rebus starring grizzled Ken Stott did.
Similarly, comedy duo Gareth Hale and Norman Pace tried playing detectives Dalziel and Pascoe in 1993 and botched it up, only to see Warren Clarke and Colin Buchanan perfectly nail the same characters a mere two years later.
There are plenty of fine and experienced actors, including Bill Paterson, Harriet Walter and Freema Agyeman, among the cast of Law & Order UK, which has defied the early sceptics by striding confidently and comfortably into a second series.
Yet nobody could have predicted that all of them would be upstaged by a comedian-turned-gameshow host-turned-Coronation Street cast regular. As Det Sgt Ronnie Brooks, the excellent Bradley Walsh is the star of Law & Order UK. He's its engine and its beating heart.
The scripts for L&O UK are facsimiles of the American originals, Briticised to suit the London setting -- and sometimes they can be overly clinical. We rarely get more than a glimpse of the characters' personal or internal lives; it's the procedure that matters, not the people.
Yet Walsh brings a human face to the rigidly constructed format. It's a lined, weathered face that bespeaks a lifetime of experience. Though L&O UK is an ensemble drama, it loses something when Walsh is off screen.
There was one small but significant scene in last night's episode, the second of the series, that demonstrated this.
Brooks was interviewing the distraught mother of the victim, an 18-year-old drug mule who'd been found dead with 70 condoms full of smack in her stomach, as she bustled around trying to locate the phone numbers of her late daughter's friends.
"Sit down, that can wait," Brooks gently tells her. It was a tiny moment -- a fleeting, throwaway scene -- yet Walsh invested it with warmth and humanity. He finds an added layer to his character that isn't always in the script.
It's natural, intuitive screen acting of the very best kind; the fact that it comes from such an unexpected source makes it all the more pleasurable. In Law & Order UK's house of cards, Walsh is the ace.
Hook in Haiti was a worthy, well-meaning documentary whose good intentions and feelgood tone have been overtaken by the tragic events of January 12.
Filmed three months before the earthquake struck, and produced in co-operation with charity house-building organisation Haven, it followed George Hook as he joined 260 volunteers to build 40 houses in a week for Haiti's poor.
As always, Hooky (68) proved a game soul, getting up at 5am to muck in with the cooking -- though his facility with an egg is inferior to his handling of another oval-shaped object. But the moment when he pointed to a newly built house and said: "This is going to say up forever," had an aching poignancy.
TOMORROW: Pat reviews The Boys of St Columb's (RTE1) and covers his ears as Amanda Holden tries country singing in Fantasy Lives (ITV)
Law & Order UK ****
Hook in Haiti ***