bearing in mind, these uni's will not want tp take too long, reading applications wont be fun and if there is a suggested deadline like March 31st then they will hit it, i am sure of it. admittedky they could take longer but i honestly dont think they will.
they will have their own targets and they will just start to put people off by not replying soon.
they ucas people will word it that way ("aim to have decision sent") so that if the uni hasn't given an offer/rejection by then, at least their back is covered (also, it would stop people woorying about a late reply).
*are you sure ? i thought it was april.*
31st March is the end of march, not april! lol!