Tomatoes suffering from cold nights

I had Tuesday off and, in between the showers, was able to spend some time in the garden. My tomato plants, which I had put out at the weekend, were looking good. Tuesday night was cold (colleagues at work living outside London had had ice on their car windscreens), I checked the tomatoes before leaving for work. They had been badly hit but had survived. Waiting for the bus home from the the local Radical History Group talk last night at ten o'clock it felt a bit nippy, but I forgot to check the tomatoes this morning. If they have no more cold nights they can recover; repeated hits of frosty weather and I won't be having homegrown tomatoes this year!