Some years ago I was going east up the A303 near Wincanton (Somerset). I was overtaking a truck and thought the motor sounded very load when a C130 appeared just to my right. They appear occasionally at low level and I suspect they use Castle Cary station (which is a junction) as a "navigation aid".
Some 40 years ago I was on a gliding holiday in the Cairngorms. One day the T21 was using the adjacent ridge when a Canberra went below it. When the T21 landed they commented that they felt a slight bump and then saw the Canberra overtake them.