Not a medical case, but an important review of the principles of non delegable duty by the UK Supreme Court (formerly the House of Lords): Woodland v Essex County Council  UKSC 66. The review is quite concise and includes commentary on the leading Australian decisions.
The school had delegated the control of the child to third parties to carry out an integral part of its teaching function (swimming lessons) during school hours, in a place where the school chose to carry out this part of its functions. If it is found that the third parties were negligent (in a later trial) then the school will be in breach of duty, being the non delegable duty, which was held to exist by the Supreme Court.
The Supreme Court now provides video summaries of decisions; the summary of Woodland appears online here.
A press summary is also available.