ANZ code share?
 

This may or may not be a silly question: I'm booked on a bmi ticket LHR-LAX rtn. on Air New Zealand metal in T class - will this earn miles as per the operating carrier rule (NZ T earns 100%) or will this map into something totally different - if so, what?

I can pretty much guarantee you that the cheap BD T fare will map onto an NZ code that earns nothing at all. The base fare is £270 less than the cheapest NZ coded earning fare on the route.

100% miles for these flights did credit after all but it had to be done manually by BMI and it took some chasing.

^ Well done. Sounds like a good result in the end. It's a long way to go without earning any miles! I you possibly got a good miles:cost ratio too?

Very interesting.....

Given how cheap the fare was compared to what you need to spend to get DC miles on an NZ coded ticket, what did BD T map to on NZ?

I never found out! The booking class is not displayed on NZ boarding passes, though it did say "Airpoints earned NIL".
But I was assured by BMI in writing before travel that I would earn 100% miles and they were manually credited as one lump sum. It would have been very annoying to not earn anything as the membership miles were needed! And flying UA in eco clearly would not have been an option. The NZ 747 (RIP!) was very comfortable, I dread to think how cramped the seating on the new 777 is.