We had a well known local plumbing company come and quote for a new boiler this morning. Out of interest, my husband asked him about heat pumps. He said if we wanted one in our 1920s semi, it would be very difficult - we would have to have all the flooring up to replace all the pipework and all the radiators would have to double in size to give enough heat and the cost would be very expensive. Ed Milliband, go and do one!