If you come up the A5 from Dirft and J18 M1, just before the truck stop on the A5 and on the left is a gated road just before a horse jumpy type field. That's the start, it runs down the back of the old BT land near the radio masts and carrys on to Hillmorton locks. Only cause we've been down it in the dry we know there is a huge dip near the little bridge. Was too chicken to go it alone, I mean what if we conked out in the middle, who'd tow us out lol :D
It's quite a tame lane but fun when wet, we went down it the week before when you could see the sides, about 1 foot less water. It's definately a bonnet coverer at the mo. Home made snorkel here we come! :D