Thanks chaps for the input. Solved!
Had my arsenal prepared - also added sunflower oil and olive oil to the list, and decided to start
with what I considered the least aggressive.
Working in quality washing up liquid, letting it do it's stuff, rinsing with tepid water, drying, working more in,
eventually I could feel the adhesive break-down under my finger tips. Then one swipe with a microfiber cloth and off
with no evidence left!
Perhaps this thread should be a sticky to help others?