You could also take them off the plant, wrap each in newspaper and place in a dark/warm place ie, airing cupboard with a ripe tomato, which will hasten ripening.
Ah yes Carlton, have heard somewhere of ripening off with an already ripe one...good idea, I maight go for that if they don't get anywhere soon !! Thanks...
I'm watching the night time weather forecasts very closely as I still have green tomatoes on my plants. As long as the overnight temperature isn't forecast to fall lower than 5 or 6 degrees I'm leaving them on the plants. If you've got some garden fleece, this will help protect them. When I get to the point they need to be picked I'll lay them out on newspaper on trays indoors. (The newspaper helps to absorb any liquid if any of them split or start going manky.)