* Fixed it! *
After replacing the replacement drop links- then removing the entire roll bar assembly, removing everything from the boot, tightening the bumper, wedging the exhaust heat shields and checking the panhard rod I finally found my problem...
Offside damper strut bottom mount loose. Not noticeable unless car rocked without handbrake on.
Have tightened with breaker bar to FT and significantly lessened the noise.. New corsa b rear shocks are already waiting to be fitted, along with alto springs, so that will fully solve the problem.
Will now repaint and rebush the rollbar as its off.