Took it for a drive today and did the brake test, still the same unfortunately. But, I did do some tests and narrowed it down to the rear passenger side of the car. By going around a left hand bend at 40km/h the squeak completely disappeared but going back the other way the squeak remained. So I assume the squeak disappears when the rear passenger side when has some load removed from it.
Something for me to work on anyway.
Something for me to work on anyway.