Cyril Smith child abuse investigation 'scrapped after his arrest'

The late Liberal MP Cyril Smith. Credit: PA/PA Wire

An undercover police operation that gathered compelling evidence of child abuse by a prominent MP was scrapped shortly after detectives moved in to make arrests, BBC Newsnight reported.

Police officers brought in Liberal MP Cyril Smith during an inquiry in the early 1980s that targeted properties in south London suspected of hosting sex parties involving teenage boys.

But Smith was released within hours of being taken to a police station, according to information received by the programme.

Officers were then reportedly ordered to hand over all of their evidence - including notebooks and video footage - and were warned to keep quiet about the investigation or face prosecution under the Official Secrets Act.

The information was passed on by a former officer familiar with the original investigation and its closure.

Newsnight was informed of the intelligence-led operation, which was believed to have begun in 1981 and involved a team of undercover regional crime squad officers.

The team targeted six or more addresses in south London, including a flat in Coronation Buildings in Lambeth - a rundown tenement block approximately a mile from the House of Commons.

The squad believed that boys from care homes were being provided "to order" for sex parties.

Newsnight said it had been told that during a three-month secret inquiry, officers gathered a substantial amount of evidence of men abusing boys aged around 14.