British Prime Minister Theresa May has defended Britain's links to defence and security ally Saudi Arabia, as Saudi Crown Prince Mohammed bin Salman met Britain's Queen Elizabeth for lunch at the start of a high profile visit to London.
A fiery exchange in parliament underlined tension in Britain over Prince Mohammed's trip, which is aimed at building a broader economic partnership between the two countries, but has sparked protests about human rights and war in Yemen.
"The link that we have with Saudi Arabia is historic, it is an important one, and it has saved the lives of potentially hundreds of people in this country," May said, pausing her answer briefly as opposition lawmakers cried "Shame!".
The debate took place as Prince Mohammed lunched with the British monarch on the first leg of trip packed with displays of diplomatic affection.
Both countries sense an opportunity to broaden their existing relationship: Britain is looking for trading partners as it exits the European Union, and Saudi Arabia needs to convince sceptical investors about its domestic reforms.
Foreign minister Boris Johnson led the welcoming party for Prince Mohammed on his arrival late on Tuesday. Wednesday's first official engagement was a trip to Buckingham Palace to see Queen Elizabeth - a rare honour usually reserved for heads of state.
The three-day visit will include a second Royal audience - dinner with the Prince Charles and Prince William - a briefing with national security officials, and a prestigious visit to the prime minister's country residence.
Buses have spent two days touring London with banners accusing Prince Mohammed of war crimes, with more planned for Wednesday before the main rally, and parliament called an urgent debate on the visit.
