this happened to my husband last year - struggled through the snow, only to find they'd closed the site. He was made to make up the time, although the unions opposed it he still had to so i'm presuming it's legal as the unions where he works are fairly arsey (they are currently balloting on strike action because their payrise isn't enough!)
there are people all over the place getting laid off or taking pay cuts and they've turned down a devcent rise (the union that is) idiots!