Well this did generate a lot of interest but then it was unusual . I am sure the explantion about the engines changing power settings may be right -I wish now I had photographed it because I cannot remember if the 'blobs' were evenly spaced or at any particiular point on the sine wave.
From pretty much underneath the amplitude of the wave wasnt very great and this would have all taken place easily within the confines of the airway as well as I am able to judge from the ground.
Looking back the trail doesnt seem to have been wide enough for a B52 and would a B52 be trucking along with all the westbound civvies anyway. If it was a single or tail engined biz jet I wondered if it could have been a yaw problem with the a/c slipping a little from side to side -I am not sure of the aerodynamics of this and perhaps yaw is divergent which this path wasnt. I am also not sure this wasnt VOR tracking as that can be seen quite often overhead of me as a/c turn of the east west tracks to ehad south for Midhurst and its quite common to see the turn go ona little too long and swing back .
Anyways generated some interest thats for sure
PB