I apologize if this has been asked before but I was unable to find any related questions.
Before I accepted the current job I got to know exactly how much another candidate who interviewed for the same role was offered. It was several thousand pounds more than what I then accepted when I joined the company, but I didn't think too much of it since he had slightly more experience and a CV slightly more suitable to the job description and this felt reasonably fair.
Half a year or so later I now feel a bit more confident about my role and I'm making a pretty good job according to my line manager. I also feel that whatever experience gap there might have been between the other candidate and me will have closed up in a few months, which is when my salary review is coming up.
I'm now considering my negotiating tactics. Of course my first approach will be along the lines of 'look, I performed really well based on XXX so I think I'm worth a bit more than what you're paying me'. I think this is the better and healthier approach. I don't want try to twist anyone's arm since the job and the team are both great and I don't want to spoil the relationships with my superiors. But I do have a nagging feeling I deserve a bit more especially if I've done well by the time the salary review comes up.
My question is: if the usual tactics don't yield the results I'd like, is it worth resorting to using the information about the offer given to the previous candidate during my salary negotiation? Is it worth trying to be honest about it and just say that this feels unfair and that for a proven track record I deserve at least as much as they were willing to offer someone with comparable experience without one?