No requirement to been seen by UK Border Agency (Passport Control). Common Travel Area (CTA) controls are usually manned by the Police for their own checks e.g. troubles in N Ireland etc. or they were probably making sure that you were not international arrivals, hence the requirement to produce your boarding card, so that those who are required to be seen by UK Border Agency are.
I do not think quoting Article 22 is going to get you far when standing in the queue, but try it and see what reply you get!
Regards
Davedog