really weird grinding noise

hi guys,

this morning my clio started making the oddest noice, i was driving on the motorway and when i came off at the junction it started to make a strange grinding noice

the only way i can describe it is its like a tree branch is stuck under the car and is dragging on the ground ( but obviously i have checked and its nothing like that lol)

the noice seems to get worse as i accelerate harder but then totally dissapears above around 70mph

wondered if you guys have ever had anything similar ?

thanks
 
sounds like some sort of gearbox bearing has failed,especially if its doing it under load then goes away when cruising