id on domestic flights is a loco thing. do you show id travelling on the enterprise to dublin or on the ferry to scotland? NO!
if you are transiting thru lhr and being issued with onto boarding pass or thru checking bags then you will be asked for your passport. if bmi was required to check all id by law then it would. if someone wants to show off their photo then travel with the loco airlines who simply glance at the id anyway.... not really paying much attention to it!!
Exactly.
On a recent MAN-LHR flight with BA we were actively told to 'put your passports and I.D's away and just hold open your boarding pass'.