The central focus of Harry's research is to develop underpinning methods to exploit the scale and phenotypic resolution of electronic health records (EHR) to accelerate early and late phase translational research. He has published over 200 papers and has an h-index of 57 with 27,657 citations. His research is cited in seven major clinical guidelines and public health policies with implications for the health of millions. As Research Director Health Data Research UK (2017–), with £120m initial investment and long term (15+ years) horizons, he delivered an historic ‘first ever’ pan London research partnership in biomedicine around his science vision across London’s five universities (Imperial, King’s, QMUL, LSHTM and UCL) establishing governance arrangements and legal contracts. HDR UK London has influenced ministerial decisions to award the Digital Innovation Hubs Programme to HDR UK.

Examples of him developing underpinning methods to exploit the scale and phenotypic resolution of EHRs to accelerate early and late phase translational research include the establishment of CALIBER (www.caliberresearch.org/) with IHI's Prof Spiros Denaxas, a web-based portal for sharing computable phenotypic algorithms and other informatics tools for the wider research community. There are currently >100 registered users and over 300 phenotypes curated,>30 publications and >1300 citations. 

Additionally, he established fundamental principles of EHR phenotyping and validity testing with multiple record sources e.g. for myocardial infarction; algorithms widely shared in UK Biobank showcase. He led the Prognosis Research Strategy (PROGRESS) MRC Partnership making methodological recommendations for improving research in outcomes, biomarkers, risk prediction and stratified medicine; 2018 being advanced in relation to AI in new collaboration with Turing Institute.

Harry's research exploiting clinical record linkages has already impacted three main areas: public health policy; international clinical practice impacting millions of patients with, or at risk of, cardiovascular diseases; and national policy on data and informatics.