Thanks for everyone's input.
So I tried olive oil - unfortunately this didn't
work.
Acetone worked but was slow going.
Lagoon have a how to guide on this - they say to use a diluted solvent. I have since found out from Lagoon that this is MEK (Méthyl Ethyl ketone). I purchased some from my local auto
paint supplier.
Applied with a soft paper towel, sticker ( or is it some type of paint) just dissolved away.
Hope this helps.