If your brother bought from a private seller ... as Graham says .. Buyer Beware.
If your brother examined the car before he bought it, then it's his own fault he did'nt spot a suspect clutch. He should have taken someone with him who was capable of inspecting the car.
On the other hand if you suspect the seller of being a car trader, then the ball falls into your court. Trading standards are very keen to get involved where someone who is a trader, is hiding under a ..'Private seller'.. blanket..!