Does my husband have a gambling problem?

This has been going on for a couple of months now ever since the Grand National races this year, my husband has been non-stop gambling on the horse racing. He's got a ladbrooks account and he only puts small amounts in like 5 and 10 pounds at a time, and he only bets small amounts on each race...I dont know exactly how much he has bought in alltogether, but he's betting on the horse racing for easily 4-6 hours a day. He sits with my laptop and is just completely fixated on the racing for hours on end, and won't even bother getting up to even eat anything. Everytime I ask him for my laptop he says "ok after this race" and then I get 5 mins to go on my laptop before he takes it off me again for the next race. And everytime I mention that he's got a problem with gambling, he just yells at me and says he can do what he wants to do, and that I "do his head in" because he thinks i'm being controlling. It always ends up in an argument. Does he have a gambling problem? Is there anything I can do?