I know you can be very sure of that and it's because their parents are from China

I was referring to non native speaking students eg other british asians, caucausians and so on.

The point from that education UK article is it is termed very important to learn either mandarin or cantonese in the UK as of now. Although from what I saw we are lagging behind the USA, they already have high school students speaking the hua fluently. Time to get in the game. As for the maths, yes you are right.