Deano remove the brake fluid bottle and dump the fluid, clean out the bottle ,
replace and refill ,then bleed the brakes , starting from the rear right the the rear left
then go to the front right then front left .
The go for a test drive ,
What i would do is remove the two rear brake drums and check the condition of all moving parts ,check that they are not sticking, check that the brake cylinder pistons move in and out freely . if all good replace .
Then check the condition of the front brakes , the sliders must move freely and the pistons must go out wards (by pressing on the brake slowly ,One side at a time )
and be able to push them back in freely , if not O/H the brake calipers.
This service should sort out your problem if not then please get back to me with the answer box below as you have done in the past .
Kindest regards Greg