Salary negotiation — how did you approach it and what outcome did you get?

I've been PM here for 3 years and haven't had a real pay review in that time — just the NHS pay uplift. I know from conversations in this community that I'm underpaid relative to peers managing practices of similar size. I want to have the conversation but I'm nervous about damaging my relationship with the Partners. Has anyone successfully negotiated a significant uplift? What approach did you take and how did the Partners respond? I'm thinking of framing it around a market benchmarking analysis.