If you have the time to mount an aftermarket gauge and devise a mount for the aftermarket sensor you certainly have the time to fix the problem properly. Did you ground the wire to the temp sensor with the key in the "on" position and observe the gauge. If the gauge went to full hot the problem is the sensor. If it didn't move and all your fuses are good, then yes, the gauge may be bad. The cluster is easily removed and disassembled to replace a bad gauge. The sensor can be removed and replaced with practically no loss of coolant (done with a cold engine and leave the cap on). Given that you cited prices in Pounds the parts clusters I have may not be of any help to you but surely there must be sources on your side of the pond. -- Dave