Where does this man stand legally?

My husband's male colleague wants to work part time (they work in a builder's merchants) so that he can be home for the kids after school but his work is saying no. I am sure there is a law which means large businesses have to do their best to accomodate parents (usually mothers) don't they? I am thinking he is getting this response because he is a man. If he cannot find part time work, his wife will have to try to reduce her hours at the bank she works at and she is up for promotion which she will not get if she is part time. She also earns more. It would be so much better if he could reduce hours. Who thinks he should claim sexism here? No women work there.