Mr Daniel Leff is a Consultant in Oncoplastic Breast Surgery and a Reader in Breast Surgery, based at Imperial College Healthcare NHS Trust, specifically at Charing Cross and St Mary's Hospitals. He also sees patients privately, including at The Harley Street Clinic.

Mr Leff completed his undergraduate training at Imperial School of Medicine (St Mary's) and qualified in 2000. He then specialised in oncoplastic breast surgery, training at several centres of excellence, including the breast unit at Imperial College and the Royal Marsden Hospital. He further honed his skills with advanced training as a National Oncoplastic Fellow at Broomfield Hospital and the St Andrew's Centre for Plastic Surgery in Chelmsford, Essex.

Holding a Master of Surgery degree in oncoplastic breast surgery, Mr Leff graduated with first-class distinction. In 2016, he was awarded the Isaac Gukas Medal for outstanding achievement in breast surgery. He also received the British Association of Surgery Ronald Raven Travelling Award, which allowed him to visit and learn from colleagues at the MD Anderson Cancer Center in the US. His main research interest focuses on developing margin assessment technologies to reduce the rates of re-operative breast surgery.

Mr Leff's areas of expertise include breast diagnostics, one-stop clinical assessment, breast surgery, breast reconstruction, and breast cancer. He has been serving in his current roles since his appointment and continues to contribute significantly to the field of breast surgery.