Thanks for the responses, chaps.

Christian McArdle wrote:

The foil/foam designed to go behind radiators would seem ideal.


I'd sort of thought along those lines but suspect this maybe little
more than the fridge has already internally. My spot check analysis
tells me that most times I go to the fridge the compressor's at work.

I'm intrigued by the Celotex idea mentioned earlier but will need to
get home and check what space / ventilation I have beneath the fridge.