Baby seagull

Hi. I have found a seagull chick. It quite a big chick with all of its grey fluffy down. It's behind a nightclub where I live and it's been there most of the day. I really don't know what to do to help it. I don't think it's injured because it's walking around. I'm concerned because the club is open tonight and there will be drunks and cruel people that might abuse it. I have tried ringing the rspb and RSPCA for advice but they are all closed. Any help would be appreciated