He qualified from Cambridge University and St Thomas Hospital Medical School, St George's Hospital and the Princess Royal Hospital.After gaining his surgeon's qualification he spent three years in Manchester and Salford, before being appointed as a research lecturer in Atkinson Morley's Hospital, Wimbledon in 1997. There he studied cerebral blood flow and ischaemia following subarachnoid haemorrhage for his MD thesis. At Atkinson Morley's Hospital he passed the FRCS (SN) and trained in all aspects of neurosurgery.Since working at Hurstwood Park Mr Critchley has developed his interests in spinal surgery, especially surgery of the cervical spine, tumour surgery and cerebral aneurysm surgery. His practice at Spire Gatwick Park Hospital reflects these interests.