Hi Steve -
Thanks for the suggestion, and also to everyone esle who replied.
I went to a Lexus service centre, they said the button is in an aftermarket fitted panel, but not to worry, as from my description of nothing happening whatever it controlled has probably been disabled. Next stop is the previous owner or if that fails the main dealer who did the majority of the servicing. If all that fails I will try and upload a photo. Cheers, BB