Just experienced a variation of this on a trip to Scotland. On the trip to Inverness, no one at Heathrow security flagged my toe nail clippers with sharp, pointy ends that are definitely less than 6 cm. On the return trip, security in both Inverness and Heathrow flagged my bag and focused on the clippers. I had to explain their purpose as toe nail clipppers, and each time, I was sent on my way with the clippers in my bag, but I was prepared for confiscation and would have simply bought another one when I got home.