Think you are right about the 757 JEM60.
About thirty years ago I attended the BAe Families Day at Dunsfold (not-that-smallish stray boys on bicycles were admitted, whether via a hole in the hedge or a more official entrance I recall not).
Anyhows, a certain Stefan Karwowski was in the hot seat of Spencer Flack's Hunter; he wound up a sizzling display with very fast banked run in from slightly behind crowd right, just clipping the corner of the crowd line where I was on pole position to cycle round to the production hangars for a quick tour before skedaddling back to school in time for high tea... Stefan, being Stefan, was low... very low... and the aural boxing of the ears that slightly trailed the Hunter was rapidly followed by a considerably more solid punch of air as the vortices came to roost at ground level.
Closest I've ever been to a fast jet at speed and the only time I've encountered vortices.
I don't know if the CAA had a word with him afterwards; the next time I saw him, he was heading straight up in a half cuban from take off, mounted in Stephen Grey's Bearcat at Biggin Hill - his second flight on type.