"Only problem with that is it feels a bit like black mail, dont you think they would despise me if we went down this road?"
Don't think of it like that. You are simply doing them a favour by giving them the opportunity to retain your highly valued services. You wouldn't simply walk and demand 'match it or I leave' Diplomacy and appreciation for the training and career thus far. I would suggest not making it all about money...what other things that could benefit you and the company could be put on the table? The best time to open a negotiation is to do so when you are in a strong position. Another attractive job offer gives that strength.
