OK, I'm with you now!
Ideally you would always be level on the Loc before GP but not everything is ideal. You say that LHR never do that. That is probably because everything is structured to put you on final outside 10nm.
At the less busy airports, you may get a 6 - 8 mile final at sometimes of the day, which requires a descent below 3000 feet to permit a period of level flight prior to GP intercept. Unfortunately there is high ground around may of our airports and so this descent below 3000 cannot be given until in the final approach funnel on a closing heading.
So, you either accept it as a funtion of a shorter final or you request a 10nm final when you're number one. The choice is yours!
Oh and while we're on the subject, why when you're number one do some of you end up at 10nm at 3500 feet at 230kts having been given range to touchdown info and plenty of room to get the height off?
Just an observation...