Welcome to Flyertalk and welcome to the BA forum.

I think we would probably need the date of your flight, the reason being that BA runs and swaps aircraft equipment around quite a bit, so row 51 could look very different depending on the aircraft type.

If you are on an A350 then note that the rows are not completely aligned, so two aisle seats in the same row are slightly off-set from each other. So the passenger nearer to the window will have to turn slightly behind to communicate to the neighbour.

There is a BA Forum Dashboard, with a lot of material in it, but it includes a seating guide per aircraft type.