Hi,

Every now and then when braking from 40-50mph or above I get a loud whirring sound from the passenger side front brake, doesn't happen all the time but when it does it's a really loud. Also before you say is it grinding - it's not as brakes seem fine.

Cheers

Chris

Pads worn, wheel bearing worn, disc worn. The usual stuff to check.

Can't hear any noice coming from the wheel and there is no play/movement

If you brake very hard does it pull up straight?

Pulls up normally its just this unusual noice

Does the ABS operate OK?

ABS is fine

Still could be the brake pads, worth changing as it would the easiest and cheapest. Early wheel bearing wear shows up during cornering or braking when the weight of the car is greatest on each wheel. If you already have checked everything visually and all looks OK then wait till the noise gets worse then it will be easier to find the problem.