I've noticed on the chart that the lowest height on the hold NE of Biggin, (ALKIN) is 1800ft.
Does any traffic ever get held down to that level and is there any chance of me, VFR in my SEP at 2400, looking down on a 747??.
That particular hold is due south of, and only a few miles away from the Dartford Bridge, a popular waypoint, so I'l be interested to know if I'm likely to meet heavy traffic there.