While the chance of getting good speakers for £35 isn't likely, you guys have to realise that this is likely a present. Also, in this day and age, it seems 'good' covers a wide spectrum. Plenty of people say the T20's are good speakers, but some say they are crap. Buying 2nd hand bookshelf speakers for £20 is great, but when buying a present for someone else, maybe not. Someone needs to buy an amp as well to go with them. That may not be ideal.
More info is needed really. OP nephew's age, and how discerning is he between what is decent quality sound, and what isn't. If he can appreciate the sound from decent quality speakers, then the T10's wont cut it. Nothing will at £35. But like I said, what a person considers to be 'good' can vary quite a bit.