The sad truth of the matter is that given the peer pressure, and the existing climate on claiming expenses is that 99% of us would have done the same as them.
"Are you sure I can claim for that? You certainly can old boy, it's all within the rules, well if your sure.
And that, my friends is all that it takes for 99% of us.
You can only trust integrity when a person refrains from going against their conscience, even if they are absolutely certain they would never be found out.