Fester -
I thought you might be interested in this picture I took on 29th November, 1998. I was flying over the West of England - near RAF Lyneham and RAF Brize Norton, for those who know the area. Altitude was 3500' which gave me a height of about 3000'.

Ideally, VFR pilots in Britain try to get above the layer of haze which we know as the inversion layer. The problem is that in the London area, VFR traffic is compressed into the levels between ground and 2400', while IFR gets the airspace from 2500' upwards. I've flown in the Chicago area, and the VFR pilot got a much better deal, even quite close to O'Hare. But when you're forced down to 2,400' that haze can be so bad that you can see nothing in front except a white void. Over water flight around England can also be quite interesting. Often there is no horizon - just a blue/grey void.