I was going up a long drag on an autoroure in France. In the slow lane, 5th gear doing about 55mph when the front wheels started to wobble violently. I pulled over thinking it was a loose wheel. I checked the wheel nuts but all was ok and nothing obvious underneath. We had an old landrover years ago would do this the odd time but it was accepted that it was a speed wobble. I think it might have just been a combination of speed, road conditions, pulling uphill etc. Any thoughts?