Not a security risk, of course, I know all passengers are screened the same no matter what boarding card they hold, but it strikes me as odd that only the locos care about who exactly is on their domestic flights.
That's very 21st century British, I can see you are actually concerned.
That worries
me.
Man has ticket, (possibly from family / mate who can't go), man passes through security, man gets on plane. None of this is actually a threat. The mindset reminds me of the chap who was fined for getting off his train at the stop before his ticket was booked to, he was nearly arrested. The harm of course was
ZERO but now it's all about the process and following lots of rules, something we do better than anyone. Think of the Italian / French attitude to terror suspects and deportation versus our own, they just chuck them out for the common good, we are terrified to step outside the process.
Being forced to carry a passport to fly from London to Edinburgh won't make you any safer, it really, really won't.