Are you sure those seats are really in the PE cabin, or just seats in the economy cabin (World Traveller) which are designated as needing elite status? Can't remember if that's even a thing in Y as you could probably pay as non-elite to get in those. For business class (intra-Europe) the first row is blocked for BA Golds.

One way to find out is to look at the booking class on the BA website (P is a PE award and X is the Y one).

BTW: for the 10K miles difference it would be almost crazy to select Y over PE.

BTW2: 'for all segments' makes no sense as PE only exists on long-haul BA flights, not on the domestic LHR-GLA leg.

BTW3: fun fact, you can book this with 16250 Avios as a BA redemption (in Y)