Here's a new set of Front Brake Wheel Cylinder Repair Seals Kits (1-1/4") for the following models from Rover -

ROVER

Rover P4 90    (** From 1956- 59 **)

(Not for earlier Rover P4 90's of 1954- 55 which used  smaller bore 1-1/8" Front Wheel Cylinders)

(** Measure if unsure **)

There's enough seals here for both Front wheels.