Cruise control stopped working.

I don't do a lot of mileage, mainly local so I havn't used cruise control for a while. However on a recent holiday traveling down to Cornwall from Kent, when I pushed the button to turn on the cruise control nothing happened, no warning light nothing. It has always worked in the past.
I have checked the fuses in the box under the bonnet and they are all alright, and according to the schematic on the lid of the box none cover cruise control anyway, and none of the relays there do either.
I have checked the fuses in the block under the dash board, they too are OK. There are some relays there but as it is a bit restricted in there I'm not sure if any of them have anything to do with cruise control. If one of the relays under the dash covered cruise control I@m sure I could get to it to replace it.
Any ideas anyone ?