Last night's viewing - Long Lost Family, ITV

The last time I cried during prime-time on ITV, Argentinian goalkeeper Carlos Roa had just saved a penalty from David Batty and England's football team were heading back home from Saint-Etienne. Now, I'm not saying that those soapy montages on The X Factor, or whatever, never moved me, but, well, actually, that's exactly what I'm saying. This third series of Long Lost Family had me in puddles. Just like a shanked hoof by an English midfielder. Long Lost Family follows a fairly simple format – researchers find stories of people who've lost their mother/brother/sisters/father and set out to seek and reunite them. Essentially, it's the last five minutes of Surprise, Surprise without Bob Carolgees and Cilla's song.

Instead of Cilla, we get Davina McCall and Nicky Campbell, both of whom have had to deal with situations similar to the participants in the show. McCall was estranged from her late French mother for most of her life, while Campbell – having been adopted as a child – tracked down his lost mother and father in the Nineties. It lends both an emotional authority that's rare to see in a TV presenter. That's helped by the unobtrusive format. Last night, we met two people who were forced to say goodbye to their closest relatives. First there was Chris. Chris's father had died in an accident when his mother was pregnant with his younger sister. Unable to look after two children, Chris's mother was forced to give one away. Cut to 50 years later – and Chris is desperate to find his sister but thanks to the vagaries of the adoption system has no idea what her name is, let alone where she might be.

Likewise, 76-year-old Polly, who was forced by a bullying father and cowardly boyfriend to give away her six-week-old son Philip at a Knightsbridge adoption agency in 1959. Both – particularly Polly – are racked with the guilt of the abandonments. There's a particularly wrenching line from Polly over shots of her revisiting the building where she last saw her son: "I went in holding a baby and came out without him. And I've never been the same since." Now, this is formatted documentary television. Of course we're being manipulated, but the fact that the producers are working with such powerful raw feeling make it unbearably powerful at times. It's not that the stories are particularly unusual – they're the kind of thing that every family tree has buried somewhere; it's just that being witness to something so personally seismic is so rare. The producers soon trace the missing relatives. Chris's little sister Susan, a nurse, is even able to tell Chris something: that his dad didn't die in Glasgow leaving his mother to head south alone; he died in County Durham, where Susan was born. The two reunite in a way only two British people could – by asking each other "Are you all right?" about nine times before an awkward silence.

Meanwhile, Nicky Campbell has been dispatched to Auckland, New Zealand, where Polly's lost son – now called Steve Hearn – has been tracked down on a hunch by the unseen researchers. When Nicky shows Steve a picture of Polly, the tears start. Not just him, but me too. We've heard Polly discuss the guilt that has eaten away at her for 50 years, but Steve has never felt any ill will towards his birth mother at all. He's had a happy life; Polly can start to forgive herself. And only by the time he gets to London, it's begun to sink in. Steve even mentions his excitement of finding someone who "looks like him". The emotion – especially when Polly is told by McCall that they've found Philip – is so real that it's almost invasive. But, hey, no intrusive TV show, no long-lost kids. Good deal...

It could do without the narrative-pushing minor-key piano music that's peppered throughout. But with fine presenters, the realest of storylines and happy outcomes (I dread to think of the stories ditched in pre-production due to dead leads), it's popular documentary programming at its finest.