MartynSinclair. I can sympathise, the problem with security is that you appear to have no rights and even begining a discussion is risky. Like you have no issue with secuiryt but I do not like the pat down either and find it intrusive. Moreover I have never had a pat down anywhere else that is like this, it is unique in my experience to Heathrow and typical of their arrogant attitude to cusotomers. A strongly worded letter of complaint is required.
I went through LHR and GLA over the weekend and as well as removing my belt and shoes (without being asked) now my watch, which I part with very reluctantly. It does not stop the radom searchs but at least is stops the machine going off as a result of detecting metal.