National PCNL Audit
British Association of Urological Surgeons has published the results of outcomes of keyhole surgery for removal of kidney stones (percutaneous nephrolithotomy, PCNL) on their website. Details of the number of operations performed by each surgeon and centre in the United Kingdom in 2014, 2015 & 2016 are given, with information about surgeon and unit transfusion rates and length of hospital stay. This has created a national platform for comparison of outcomes between surgeons and hospitals and sets the standards for high quality surgery.
As seen in the link, Mr.Subramonian has performed the second highest number of keyhole procedures (per surgeon) in the UK and has very good outcomes.