A Catholic priest has been arrested in connection with alleged child abuse at a London guest house during the early 1980s, his diocese has said.
Operation Fernbridge is looking at claims that senior political figures and others sexually abused boys at the Elm Guest House in Barnes.
The Diocese of East Anglia said one of those arrested is 66-year-old priest Tony McSweeney, from Norfolk.
The other is a 70-year-old man who was arrested in East Sussex.
Father Mark Hackeson, of the Diocese of East Anglia, said: "The church diocese takes safeguarding of children very seriously and so we will be co-operating fully in any way with the police investigation."
Scotland Yard said the allegations were not connected with current residents of the former guest house, which has been converted into residential flats.
It is also investigating links between the guest house and the nearby former Grafton Close children's care-home run that was by Richmond Council.
The 70-year-old arrested man, from St Leonards-On-Sea, is understood to be John Stingemore, who used to help run Grafton Close, which closed some years ago.
BBC News home affairs correspondent Danny Shaw said the police investigation centred on claims that the guest house was used by people to abuse boys from the home.
The allegations were investigated at the time but resurfaced in October after Labour MP Tom Watson raised the case in Parliament and called for further inquiries.
Mr Watson had been passed information by journalists working for the investigative news website Exaro.
Commander Peter Spindler, head of the Metropolitan Police's Specialist Crime Investigations unit, said the "complex multi-agency investigation" was supported by the NSPCC charity, the Child Exploitation and Online Protection Centre and Richmond Social Services.
He said anyone affected by, or with information about, activity in the early 1980s at the guest house or care home should contact the NSPCC or police.
In a statement, Richmond Council said it considered "the safeguarding of all children and young people as an utmost priority and we take any allegations of abuse very seriously".
A spokesman added: "We are offering our full support and co-operation to the police during their investigation. As the investigation is ongoing, it would be inappropriate to comment further at this time."
The NSPCC said its helpline number 0800 800 5000 was staffed by trained counsellors 24 hours a day. People with information could also use the email address firstname.lastname@example.org to contact them.
NSPCC helpline director Peter Watt said: "We will assist the police in gathering evidence and supporting those who come forward. It's important we recognise the massive impact abuse has on children and young people, often well into their adult life."