Thanks Mainladdee. Found the article very interesting. There were some interesting explanations given about why it is extensively used in Norway. I hope that there is some way of getting a comparative cost per kwhr for electricity. The Norwegians seem to have extensive inexpensive hydro electric power which can run the fans and keep the system working. They also have very well insulated buildings. I think these two factors play a significant role in making heat pumps work.
I just replaced my combi boiler. For about £2000. Discussed a heat pump option. Would need to replace the entire radiator system and the cost of the system seemed to be £10k plus, plus all the disruption of the radiators ot being exact same sizes as the existing ones. There is also the point made that you need electricity to make the system work. Not sure the comparative amounts of electricity needed to run a gas fired central heating system compared with heat pump system. Think it should be quantified because if you take out gas as a heating system then how much more electricity do you need to replace it as a direct heat source because heat pumps will not be able to be fitted to many homes.