The top private hospital where Kate Middleton was treated ahead of her cancer diagnosis has come under investigation for a royal data breach this week.The Princess of Wales, 42, announced she is being treated for cancer in a video message to the nation on Friday.Her diagnosis came after undergoing abdominal surgery at The London Clinic on January 16 this year.Earlier this week, it was reported by the Daily Mirror that at least one worker at the clinic had looked at her medical records without authorisation.A probe was launched into the hospital which has a lengthy history of treating the Royal Family as well as actors and politicians.The London Clinic’s chief executive, Al Russell said: “all appropriate investigatory, regulatory and disciplinary steps will be taken”.The UK’s privacy and data watchdog, the Information Commissioner’s Office (ICO), said: “We can confirm that we have received a breach report and are assessing the information provided.”Kensington Palace have declined to comment on the alleged incident.King Charles, who is also currently undergoing treatment for an undisclosed type of cancer, was also treated at the centre for an enlarged prostate this year.The London Clinic was officially opened back in 1932 by the then-Duke and Duchess of York.It was the brainchild of a group of Harley Street doctors who set out to plan a new nursing home using the highest medical standards of the day.Charles, who was previously the Prince of Wales opened the physiotherapy department in 1989, while Princess Margaret launched the MRI unit in 1991.The late Queen Elizabeth unveiled a new cancer unit in 2010.Previous royal patients in the clinic include the late Duke of Edinburgh, Prince Philip and the late Queen's younger