Last Night's TV: The Choir That Rocks/ITV1Breaking into Britain/BBC1The Shadow Line/BBC2

"Have you heard of Rock Choir?" This was the question I spent much of yesterday asking. I asked colleagues. I asked friends. None of them had. "Is it something to do with Gareth Malone?" said the assistant features editor. "Noooo," I chanted, rolling my eyes. "It's a phen-om-en-on." The truth is, until The Choir That Rocks, I'd not heard of it either.

The problem's clearly us. Because Rock Choir is, by all accounts, a phenomenon. It has seven-and-a-half-thousand members, making it the largest contemporary amateur choir in Britain. In May, those members filled out Wembley Arena to give a special performance of their repertoire (which, based on last night's renditions, seems to bear a striking resemblance to the Magic playlist).

It's all the brain child of Caroline Redman Lusher, herself a former would-be pop star. She came up with the idea, devised the training programme, and oversaw its expansion. Closely. She's incredibly shrewd; that was made clear in her every move, from the contact she maintains with every teacher, to her ideas for recruiting new members (on which more later). Both choristers and instructors talk of her with an almost religious reverence. There might be such a thing as a half-hearted Rock Choir member, but we didn't get a glimpse of them last night.

Instead, we got Angie, who joined while in remission from cancer and sees it as a kind of "vocal physiotherapy". And Brian who is, he said, "a little bit put out that they don't do any of Cliff's." And of course there's Chris and Izzy who joined in their retirement and now spend much of the day, headphones plugged in, pottering around their home singing aloud to no one in particular. It's like One Flew Over the Cuckoo's Nest, only rather sweet, especially when they invite the local town crier round to practise his dance moves with them. Much of the credit for this enthusiasm lies with the choir's teachers. The model is a curious one: few appeared to be doing it out of ardent love for the concept, most out of economic necessity. But almost all seem to want a long-term career in it.

It's both rather fascinating and rather sweet – English eccentricity and its most eccentric. There's a bit of dramatic narrative, thanks to Caroline's Wembley stunt. Most of the filming was done in the run-up, so the event is given the can they/can't they treatment. The cliff on which the operation hangs is Yorkshire. The Northern contingent isn't quite as enthusiastic as Caroline's original Surrey crowd and it's down to two new teachers, Stef and Nick, to work up a frenzy, a prospect that looked unfeasibly remote as Nick faced his village hall half-dozen or so. To aid the pair, Caroline planned a singing flashmob in a local shopping mall, transporting her Farnham crew up to bolster the ranks. Whether the stunt delivered any new members remains to be seen – that's for episode two – but there's no doubt they pulled it off with aplomb. More than that, it looked jolly good fun. I wouldn't mind signing up myself.

There wasn't much new about Evan Davis's Breaking into Britain, but that didn't detract from its merit. Despite the tone of the title, it was, in fact, a largely sympathetic look at the lengths illegal migrants will go to in order to set up home in Britain.

It costs £8,000 to make the journey from Afghanistan. They do it because they want jobs, education and homes. The average national life expectancy is 44 and incomes are low; raising that sort of money means selling one's home. People-smuggling is a growing industry – professional smugglers dot the markets – but those looking for a cheaper route attempt it alone. Their journey takes in Iran, Turkey, Greece and Italy. Many get halfway, run out of money, and wind up stuck. By the time they arrive in Greece, expecting Europe and its great riches, they're forced to live on the streets, bemused by their poverty and longing for home.

The trip from Africa isn't much easier. People flock from across the continent to collect their false documents in Nigeria (a snip at £72), and then attempt to make their way through Morocco, into Spain, then to Calais or Ostend. Many don't make it, winding up stranded on Britain's doorstep. For women, the journey is particularly treacherous: the most harrowing account was given by a women raped in front of her four-year-old daughter. When her attackers were done, they attempted the same with the child.

So why do they keep coming? Throughout, there was a constant theme: the migrants' surprise that this was what their journey had come to. I wish this had been explored a little more: who propagates the idea of Britain as an easy land of opportunity? Not enough light was shed on the question, though a shaft of illumination came during a conversation with an Afghan attempting to leave Greece by clambering on to lorries. "What do you tell everyone back home when you speak?" asked Afghan reporter Shoaib Sharifi. "We tell them that everything's fine, that we have a nice room," came the reply.

And a final word on the final episode of The Shadow Line (if you're iPlayering it, look away now). Surely much of the enjoyment of these gritty gang-and-crime dramas comes from trying to figure out whodunit? Perhaps we should have known that in this case, that would be impossible. Following each episode required enough guesswork as it was. But, really, Lia?

a.jarvis@independent.co.uk; twitter.com/aliceazania