Photos: Saudi Crown Prince meets Queen Elizabeth on UK trip
London - Prince Mohammed's trip is aimed at building a broader economic partnership between the two countries.
Prime Minister Theresa May defended Britain's links to defence and security ally Saudi Arabia on Wednesday, as Saudi Crown Prince Mohammed bin Salman met Britain's Queen Elizabeth for lunch at the start of a high profile visit to London.
Prince Mohammed's trip is aimed at building a broader economic partnership between the two countries.
"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 in parliament.
The parliament debate took place as Prince Mohammed lunched with the British monarch on the first leg of trip packed with displays of diplomatic affection designed to help the widen longstanding defence ties into a more far-reaching partnership.
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.
Prince Mohammed was due to meet May later on Wednesday.
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 Saudi delegation will meet May and senior ministers inside May's Downing Street offices to launch a UK-Saudi "Strategic Partnership Council" - an initiative to encourage Saudi Arabia's economic reforms and foster cooperation on issues such as education and culture, as well as defence and security.
Britain is vying to land the stock market listing of state oil firm Saudi Aramco, but no decision is expected this week.
"We would like the Aramco share option to be issued in the UK and we will continue to suggest the City would be the best place for it," junior foreign office minister Alistair Burt told parliament.
Later this month Prince Mohammed visits the United States, which also wants the lucrative listing, although sources said both countries may miss out.
British officials were privately delighted at the decision by Prince Mohammed to choose Britain as the major western destination on his first foreign trip since becoming heir to the Saudi throne last year.
The British government is keen to develop a two-way trade and investment relationship, eyeing both an expanded market in Saudi Arabia for service sector exports, and attracting Saudi cash to finance domestic projects.