Hi Nick, It happens to the best of us! I have a BMW 3 series everyday car, and it developed that familiar wheel bearing droning at 60 mph. We traced it to the front right, and ordered up the bearing and fitted it. On road testing the car after, total misery as the noise remained! We swapped the front and rear wheels, on that side, and bingo, the noise moved to the back. When we examined the tyres, the tread bocks on the inner edge had worn more at the back than the front making them slightly wedge shaped. Whilst not visible to a casual look, it was enough to cause the noise. This is not likely to be your problem, but it goes to show how we can all be wrong footed! If possible I would do as already suggested, and swap the wheels around to see if the vibration travels with a particular wheel. If not, then the focus can change to the rotating components, hubs and brake discs all round, and the drive shafts, diff, prop shaft, clutch, flywheel and eventually engine. We all love a challenge! Anyone want a perfectly good but used wheel bearing?