The term seems to be associated with the expression "He knows the right buttons to push", that is he knows how to persuade people (in an organisation perhaps) to provide the result he wants. But you've made me uncertain now - beset by doubts I am - as to whether this is typical UK usage or just what I *think is typical UK usage!

I too have read the term applied sexually, but can't speak for its accuracy as my formative years preceded the rediscovery of sex in the UK. We're typically a number of years behind America in most things.