Investigations into how confidential patient records were found in a Potters Bar road have failed to attribute blame for the security breach.

Details of serious illnesses and outpatient forms belonging to patients at St Bartholomew's Hospital, Whipps Cross University Hospital and London Ambulance Service ended up strewn across the country lane in Coopers Lane, near Potters Bar, in January.

An investigation by Bywaters, who were contracted by Whipps Cross to handle disposal of waste including medical records, concluded that its procedures are "robust."

A separate investigation by the London Ambulance Service failed to reveal any problems.

A spokeswoman for Whipps Cross said: "The trust is confident that its internal procedures for the disposal of confidential waste on-site are robust.

"The trust has received written assurance from both Bywaters and its sub-contractors that its confidential material will only be disposed of at the site the trust has visited and quality assured."