In the Vic on Sunday I decided to ask the guy behind the card desk if he knew why this rule was in place as it seemed confusing to me.
What I didn't know was that this man, the grumpiest old git I have spoken to in ages was unfamiliar with normal human interraction and politeness. He stated that the rule was in place because when heads up it 'doesn't matter if you get underraised as it doesn't affect any third person in the pot'. When I questioned this the grump repeated what he said almost word for word and then went back to his bulldog chewing a wasp face. I should have just waited for AlrightJack to come back.
Couldn't of had two more different staff members. One a complete tosser and one helpful and friendly.
/Rant
Well, that's one way of looking at things.
Yes having str8s beating flushes wouldn't affect a 3rd player either, but it would clearly affect a visitor to the club who quite naturally would assume that the uk's "flagship casino" used standard rules.