Thanks for all the comments.... in no particular order ...
157590 miles
No sign of leaking ATF at all, box is dry as is the floor
No idea how to check the flexplate versus the box .. I assume the worst ...
(guessing that it needs dropping anyway)
Sounds far worse than a thrust washer .. the high pitched sound was like a bandsaw ... so perhaps one of the brake bands has given up ...
Vibrations "might" be the wrong word .. the whole car was "shuddering" quite markedly for the 6 feet it moved, it sort of felt like you were driving with a wheel clamp on.
Once stopped, switched off, good look around/under .. nothing visual so tried it again .. all the noises and shuddering but no movement in any gear, so switched off and left off.
Guy up the road suggested the diff had seized .. I discount that as in neutral it rolls quite easily and quietly.
Think thats all I can add right now ..