I wouldn't worry too much McC--after automatically removing my shoes (they're clogs with lots of metal staples so always ring the x-ray bells) at Heathrow I was actually ADMONISHED to put them back on! I am infamous for being secondarily screened in US airports so practically remove everything (well, not everything--not that I haven't had THOSE scans as well!) that might ping when I go through security.
When I advised the security gent that my shoes were highly likely to fail the scan--he said, "We don't do that here."
I did go ahead and send my shoes down the chute and walked stockinged through the scan, but laughing all the way.
I have found security at small sites like Southampton airport to be far more restrictive than Heathrow.
RR