I have two BPs, one for Y and one for J - both say I can take "1 bag+laptop/briefcase". The post you refer to says the correct amount is "2 bags+laptop/briefcase" whereas clearly the correct amount here is "1 bag".
Obviously I am aware of the correct situation, however I wonder how many ex-LHR pax believe what BA print on the BP (and why on earth shouldn't they believe that) and then get hassled at security? If I have it in black & white from BA on my BP, then it seems reasonable that I should believe that.
Last month, my BPs just said "please check ba.com" under then handbaggage section.
It's not only LHR passengers getting this on their BP.
My PYOBP for a flight from LGW tomorrow also shows:
Hand baggage allowance: 1 bag+laptop/briefcase
How confusing.