A network of hidden cameras a world-renowned doctor used to spy on patients, friends and colleagues has been revealed after he was jailed for eight years.

Hearing specialist Dr Lam Hoe Yeoh captured footage on a range of devices, including cameras fitted to toilets and even hidden inside pens and watches, to secretly record victims across the country.

The 62-year-old, from Malaysia, admitted fixing the tiny devices to toilets in St Anthony’s Hospital in North Cheam, south London, as well as medical premises and train toilets across the UK, for his sexual gratification.

He was caught when a camera he fixed at privately-run St Anthony's fell from its hiding place and was discovered.

Shocked staff found images of themselves on the camera, along with footage inadvertently capturing Yeoh fixing the device with Blu-Tack.

Police have now released the 20 second clip of Yeoh fixing the camera into place.

Yeoh admitted seven counts of voyeurism, six counts of making an indecent photograph of a child, and one of possessing extreme pornography when he appeared at Croydon Crown Court in south London.

Sentencing Yeaoh to eight years in prison today, of which he will serve five before being released on licence, Recorder Warwick McKinnon described the offending as "nefarious and despicable".

He said: "The sheer scale, the gravity, the ingrained and compulsive behaviour demonstrated by the offences is significantly important.

"You are considered a high risk to the public.

"(Had you not been caught), I have no doubt that this prolific offending on a hitherto unprecedented scale would have continued."

Speaking outside court, police said Yeoh was "one of the most prolific non-contact offenders ever investigated".

Victims as young as three were discovered on 1,100 images and video files found at Yeoh's home in Banstead, following his arrest in April.

Prosecutor Peter Clement described the offending as "sophisticated, organised, planned and long-running", and said the renowned doctor "grossly abused" the high degree of trust placed in him.

He said: "The (voyeurism) offending was vast and beyond any previously investigated by the Met.

"His intention was sinister, indecent and criminal."

The court heard while the offending dated back to 1 January, 2011, the behaviour was likely to have started earlier as it would take another two years for police to examine all of the files discovered.

The footage was captured on a network of devices including pen drives and camera watches. It was then labelled with "graphic descriptions", including dates and names.

The offending took place in locations across the country, including Portland Hospital in central London, and medical facilities in Exeter, Sutton, Nottingham and Thames Ditton.

Defence counsel Sally O'Neill QC said Yeoh, who is said to have obsessive compulsive disorder, felt the "most enormous relief" when his actions were discovered.

Speaking outside court, Detective Constable Aaron Moon praised the victims for coming forward.

He added: "In carrying out his well-organised campaign of making opportunistic images of both adults and children, Dr Yeoh abused his position of trust for his own sexual gratification.

"With images of people filmed in consultations and lavatories, his footage is truly appalling and abhorrent.

"We believe he (Yeoh) is one of the most prolific non-contact offenders ever investigated by the Metropolitan Police or any other police force in the country.

"But now the lie he has led for many years has been exposed and he has been forced to answer for his actions."

The judge gave Yeoh limited credit for his guilty plea, but said he considered him a danger to the public.

Yeoh, who has already applied to be struck from the medical register, was given an eight-year term for six counts of making an indecent image of a child, of which five years would be served before being released on licence.

He was given 17-month jail sentences for five counts of voyeurism, nine-month terms for two further counts of a similar nature, and a nine-month sentence for possessing extreme pornography.

All sentences will be served concurrently, meaning he will spend five years in prison.

He must also sign the Sex Offenders' Register for life upon release.