Engine fire

Just completed a high speed 350+ mile trip from south west France, got all the way to the shopping centre close to home and smelt burning. Lifted the bonnet and found flames coming out of the wiring just behind the engine, drivers side. I poured a pint of milk over the area (all I could think of) to douse the flames and left the bonnet open for 30 minutes, then fired up the X Type ... the battery light was on, no other consequences (so far). The sheathing was burned off, I wrapped it in insulating tape and drove home. The wire doesn't appear to be connected to anything ... but that could be because it burned off. X Type 2.2 Diesel Est. I can assure you I was very shaken ... only pleased it happened after I had parked up.  Can anybody tell me what the wire is please (big circle ... small circle my insulating tape)? The second image shows the cable after taping. Any help appreciated. Problem is, I can't find what it attaches to!!!