Hospital staff were checking instruments prior to using them, when they noticed that some of the instruments had moisture on them which would not normally be there.

BBC: Medical tools

It is thought the hospital had relied on the agency checking the worker's criminal record bureau (CRB) check status.

BBC: Southend Hospital investigates sex offender employment

But it was diet that fascinated sister Elsie, and in 1933 her researches took her to the kitchen of St Bartholomew's, a London hospital, where a young doctor, Robert McCance, was checking on the cooking.

ECONOMIST: Elsie Widdowson