Vibrating/Whirring noise from front end

[FlameR]

Every now and again when my engine is on, there's a really loud whirring/vibrating noise coming from the front end of the car.
I had a check under the bonnet last night with the engine still running, and it seems to be coming from behind the N/S headlamp, in one of the connectors.

Any clues to what it could be and how to fix it?

Cheers
Ste

 

[FlameR]

bump