An ex Scotland Yard detective has extraordinarily claimed that police covered up a serial killer who stalked and killed 18 people on the London Underground.

The killer murdered his victims in the 1970s by pushing them onto the tracks and former policeman Geoff Platt has alleged that police deliberately kept the case from the public so as not to cause widespread panic.

Mr Platt said that he listened to Kiernan Kelly confess his crimes to police first hand after he was picked up in 1984 for being drunk and disorderly.

Having brutally murdered his cellmate, William Boyd, Kelly allegedly told police about his violent rampages on the Tube system while being questioned.

Mr Platt told The Daily Star: “He was high – high on adrenaline, testosterone… aroused. You could see it in his eyes.

“He was proud of that murder and when we went to speak to him he just confessed to killing 18 other people.”

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Police went on to uncover a number of suicides on the Northern Line which appeared to correlate with the details that Kelly gave to police.

However, Platt claimed Kelly was only jailed for two previous murders and that police deliberately kept the details of his alleged killing spree away from the public.

He added: “It was a coverup. Think about it, the police don’t want it getting out – there would be mass panic.

“They didn’t want people knowing a serial killer got away with pushing innocent people on to the tracks – they’d be afraid it could happen again.

“The public would stop using the Underground which would put more traffic on the roads. It would be chaos.”

The British Transport Police asked Mr Platt, who has written about the crimes in his book, The London Underground Serial Killer, to provide any evidence he has to them.

A spokesman said: “We are aware of the claims included in this book but given the passage of time since they are alleged to have been committed these would prove difficult to substantiate without further evidence.

“We would invite Mr Platt to submit any information he has on these matters to us.”