Diarmuid graduated in 1997 from University College Dublin. His first job was working at the RSPCA Animal Hospital in Manchester, where he gained experience working in a very busy clinical environment. He then gained experience in an emergency clinic before moving on to work in a small animal first opinion private practice. In 2000 he teamed up with Gavin McCoubrey and established Tameside Veterinary Clinic He has an interest in medicine, orthopaedic surgery and ophthalmology. Diarmuid has a pet cat, rescued from an animal shelter where he used to help out.