Recently I passed through the security screening at the BA First section of T5 at LHR on 3 separate occasions. With the exact same contents in my bags, I had no issues, without any need for secondary compared to the 2x out of 3 that my bag was shifted to the secondary screening while at AMS. I really give up, don't understand why Hal1 security is such a PITA (now that I know they are different companies) has such badly trained staff or machine. Really frustrating.
Cheers!