I recall travelling through Heathrow and reaching a security check with an ominous "Wait here" line. Having just come from the States I obeyed it, having been yelled at for this over there. The guard looked up after a few minutes and politely enquired as to why exactly I was standing around like some kind of lemon and would i like to come forward.
I mentioned I was just in from the States and he said "Ah, right, well we're not all wankers here". I nearly fell over laughing.
Although my best experiences have been in Irish airports. My fellow countrypeople are very laid back