In its wide-ranging report, the cross-party home affairs committee said MPs had visited Portugal as part of attempts to understand different systems of decriminalisation which were being used around the world to manage the harm of drugs, rather than just hand out penalties for their use.

BBC: Cameron rejects decriminalising drugs

Earlier this month, the cross-party Commons Home Affairs Committee urged the government to establish a royal commission to consider alternative policies - including possible decriminalisation.

BBC: Call for new drug policy research body

The cross-party delegation from the Bundestag's EU Affairs committee was in London to highlight Germany's growing alarm at the danger of a possible UK exit.

BBC: German MPs warn UK EU exit would be 'economic disaster'

Mr McDonnell, who is an MP on the Northern Ireland Affairs Committee, switched roles to give the committee evidence on behalf of his party.

BBC: Sinn Fein gives evidence to Westminster committee

Respected former finance minister Manmohan Singh chairs Congress's new committee on economic affairs, former external-affairs minister Natwar Singh devises the party's foreign policy and so on.

CNN: EDUCATING SONIA