DAVINA McCall and Nicky Campbell. Her: appearing in exercise DVDs, hair dye adverts, and soon to be seen on a new darts show that is not, alas, Bullseye. Him: putting the world to rights on the radio most days. Separately, they are benign forces. But put them together in a quest to unite long lost relatives and kaboom! Emotional Armageddon. Defcon two-level lip-trembling. Sodden hankies fluttering across the land, signalling surrender.

Yes, Long Lost Family (STV, Wednesday, 9pm) is back and it had a doozy of a story this week. In what was a first for the show, Scots-born Andy McNicol was looking for the birth son who had been adopted against Andy’s wishes. With a system designed to protect the identity of adoptees, what chance did he have of finding his lad?

Enter a special liaison officer, and before one could say “I didn’t know such a process existed” the boy, now a hulk of a man, was traced to New Zealand and Nicky was paying him a visit. Cue tears. Back in the UK, Davina was doing the same with Andy. More sobbing. By the time father and son were reunited, over a pint of course, there could not have been a dry eye in the land. Except for TV reviewers in Scotland. We are trained by Shaolin monks and the SAS to remain above the emotional fray. It just so happened, however, that at that precise moment a mote of dust flew into my eye. While it might have looked to the untrained eye as if I was greetin’ like a lost wean, I was not. No sir.

I bet Ross Kemp was bubbling. Sure, he played hard man Grant Mitchell in EastEnders, and in his subsequent career as a documentary filmmaker he has met some of the world’s most dangerous characters, but he is fooling no one. This week in Ross Kemp: Extreme World (Sky One) the baldy mush-bucket was in Naples to get the low-down on the Camorra, a crime syndicate as chaotic as it is deadly. There was a fair bit of chest puffing on show, but none of it from Kemp, who remained quietly and impressively assured throughout, as when he interviewed the father of an innocent teenager shot dead in the crossfire. As the man choked with emotion, Kemp put a big paw on dad’s shoulders. One could not imagine any journalist getting away with this, but Kemp is less a routine reporter and more of a well-informed geezer on his travels, letting the audience keep him company for a bit. It works.

If Kemp ever fancies venturing to the highlands and islands (Ross Kemp: Extreme Knitwear? Ross Kemp: Extreme Midges?) he better choose his travel dates wisely. As could be seen in Orkney: When the Boat Comes In (BBC One, Monday), the joint is jumping now that it is the “cruise ship capital of the UK”. On days when the big ships call, the population of Kirkwall can almost double. But how much benefit do the locals derive from the visitors who call in for the day? The film did not find much in the way of complaints, just a few folk raising mild grumbles about traffic and tourists eating on the boat rather than in the local cafes.

Casualty (BBC One, Saturday) bowed out for this series with a special episode shot in a single, continuous take. It’s the kind of thing a programme does when it has been going since A&E consisted of strong whisky and saws.

It was a fine technical achievement, but with nowhere to hide it also showed up the varying levels of acting talent among the cast. Let us just say some of them better pray this gimmick is not repeated.

Old People’s Home for Four Year Olds (Channel 4, Tuesday/Wednesday) took a simple idea, pioneered in the US, and toddled merrily with it. For six weeks, a group of 10 nursery schoolers visited 10 old folk in the hope that it would lead to improvements in the the latter’s mood, mobility and general mojo.

The project had its doubters, chief among them Hamish, aged 88. Hamish, who had not had much to do with children in his life, predicted that the scheme would be “a total disaster”.

Cut to several weeks later and a game of sleeping lions featuring Hamish, who the teacher was sure had fallen asleep on a beanbag.

“ROAR!” went Hamish the lion, sending the crowd of giggling and screaming four-year-olds scattering. In a similar vein, another resident who began the experiment walking stiffly and slowly with the aid of a frame, terrified of falling, was last seen running – RUNNING, PEOPLE – with her two-foot-high partner in a sports day relay race.

Whatever happens at the World Athletics Championships, Usain Bolt will have to shift some to beat that sight.