I deleted what I wrote previously. I misunderstood you at first. Strange that BA is calling it Premium Economy when thats a different seat type than MCE. After looking at the map you're definitely in MCE which does give you extra leg room, although I'm not sure of the actual measurement in row 10. I know it's been reported that it's not a full wall, but a partial wall in from of MCE/ behind PE.

I just called to upgrade my ticket for next month from PE to Business and they wanted $7k for two people round trip. Nope, not doin it!