Part of the problem, and this is not only applicable to BA but other airlines too, is that often in today's world, the premium economy cabin has far less seats in it than the business cabin. Thus it purely becomes a supply/demand issue.

Frankly, I had high hopes for Premium Economy. For day time flights it's a completely acceptable experience for my wife and I. So I was hoping we'd be able to book J for the outbound/redeye flights then PE for the daytime flight home and save a little money. But the low number of seats in the PE cabins mean this just didn't pan out.

Regards