removing rear bench seats on 1996 Defender 90 300tdi

Hey all. I am trying to remove the rear bench seats on a Defender. They look like Britpart aftermarket type. There are screws on securing them on the wheel arches but according to the instalation manual (did not fit them myself) there are some flaps that slide into a slot.
To remove, I removed the screws, but for the life of me I cannot take them out of their slots. I can lift them up a few cm, but I cannot pull them out as the skeleton of the seats meets the wheel arch. Spent more than two hours on this and cannot figure it out.
Any tips?

From memory, the flaps on the seat backs slot into gaps in the body capping. (Military inward facing seats.) Assuming that yours are the same design, removal was just a case of removing the bolts through the seat base, four bolts per seat.