Back in the days of the old low level route in the 60's and 70's you could pick a spot and given the right weather be guaranteed a continuous procession of everything based in the UK at the time, from Vulcans, through Buccs down to JP's. I remember taking my wife to Aysgarth Falls in the Yorkshire Dales, smack on the centreline of the route, supposedly to admire the view, but she became suspicious when every 5 - 10 minutes my gaze was turned upwards! I ended up on Victor tankers, where FL250 was considered low level, but I did once turn down the chance to go round the route in the back of a visiting B52. I didnt reckon my stomach was up to it that day, but I've been kicking myself ever since.