Mr Gullan qualified from the Medical College of St Bartholomew's Hospital and was appointed as House Surgeon to the Professorial Surgical Unit in 1978.
Mr Gullan obtained membership of the Royal College of Physicians in 1983 and subsequently Fellowship of the Royal College of Surgeons in 1984. His neurosurgical training started at Addenbrookes Hospital, Cambridge before moving on to Edinburgh. He then returned to London as Senior Registrar to the Guys'/Maudsley and Brook Regional Neurosurgical Units, with further time at The Royal National Orthopaedic Hospital, gaining more experience in complex spinal surgery.
He was appointed as Consultant Neurosurgeon to the South East Thames Neurosurgical Unit in 1988 where he continued to develop his major interests in spinal neurosurgery and management of brain tumours.
His career has given him the opportunity to present work in these fields, particularly complex cervical disc surgery in over twenty countries and author and co-author numerous papers and presentations in this work.
Mr Gullan has served as a member of the Council of the Society of British Neurological Surgeons and acted on various committees of the Royal College of Surgeons over the years. He is currently a member of the Advisory Committee to The Blackheath Hospital. He also performs general spine care services.