Medical practitioner – Negligence. On a balance of probabilities, had a second on call registrar been called at a time when he ought to have been called, during the claimant's birth, the delivery time would not have been any different than it had actually been. Accordingly, the Queen's Bench Division held that the resulting birth asphyxia causing the claimant's cerebral palsy had not been avoidable had the defendant NHS authority not breached it's duty of care by calling the second on call registrar when it ought to have done during the delivery.