Help Me Help My Child (C4); The Choir (BBC2): Eight-year-old Danny has a man living in his head called Idiota, who threatens him and tells him to do harmful things.

He believes if he eats certain foods he'll die. And if he picks up a knife, "he'll make me stab myself in my head".

Jack, 15, is obsessed with perfection and cleanliness. Unlike most teenagers his age, his room is spotless and tidy as he spends hours cleaning it. Both Danny and Jack have OCD - obsessive compulsive disorder, a mental condition that traps a child into repeating actions obsessively. Curing them isn't easy but with cameras allowed into London's Maudsley hospital for the first time, we could observe their pioneering treatment for children with OCD in Help Me Help My Child.

This was fascinating stuff, once you got over feeling like an intrusive onlooker as the children's anxiety levels were pushed to the limit to "cure" them.

Idiota is how OCD manifests itself in Danny. Clinical psychologist Hilary Mack worked patiently with Danny to overcome his obsession. The scene where Danny was set his most difficult challenge to pick up a knife was uncomfortable, almost unbearable, to watch. The first attempt ended with him cutting his finger, then writing the words HELP ME in his own blood on the window.

Jack's big test was "torturing" one of his beloved magazines, which he kept in pristine condition in a sealed wrapper. Just tearing the corner off one page took supreme effort.

It was tough for parents too as they're asked not to comfort children as they're put under extreme pressure to resist their obsessions.

The children that choirmaster Gareth Malone wants to help in The Choir are from what was called "a typical comprehensive school" in an area of relative social deprivation in Middlesex. His goal is to find 25 people to sing in a choir and enter the Choir Olympics in China.

The first problem was the school's lack of choral tradition, but if anyone was going to gain the confidence of the youngsters, it was Malone, mainly because he only looks about 12 himself.

The girls who auditioned raised his hopes. Then came the out-of-tune boys to dash his hopes. The film-makers were luckier to find good human interest stories among the hopefuls, like the brother and sister waiting to hear if their father would be given permission to join them from Kenya, and the girl who was persistently late for school.

What was surprising was their almost total lack of confidence when it came to singing, despite their outward bravado. Then again, he was asking them to master four-part harmony, something most had never heard of let alone sung.

No wonder that, at one particularly banging-head-against-brick-wall moment, an exasperated and disappointed Malone exclaimed, "Bloody hell, what have I taken on?". More than he could chew was the expression that sprung to mind.