"This is a significant boost for United Kingdom prosperity and a clear demonstration of the strong worldwide confidence in our economy as we prepare to leave the European Union", a Downing Street spokesperson said in the statement.
UK Foreign Secretary Boris Johnson also greeted the Crown Prince at the bottom of his plane when he landed on Tuesday night.
"Hopefully by next year there are going to be way more rights given to Saudi women, the ones that we deserve", she said. Later Wednesday Prince Mohammed was due to be hosted for dinner by heir-to-the-throne Prince Charles, with Prince William among the guests.
During the hour-long visit at Lambeth Palace, the pair discussed the crown prince's reform plans, and Welby - the head of the Anglican church - expressed his concerns about the treatment of Christians in Saudi Arabia.
Vans featuring a welcome to the Crown Prince of Saudi Arabia, Mohammad bin Salman are parked in Whitehall in central London.
Campaigners say that a government that respects human rights would suspend arms sale to Saudi and demand greater transparency from the industry as a whole instead of "hosting the architect of war in Yemen".
Lambeth Palace The Crown Prince has faced significant protests over Saudi Arabia's involvement in the conflict in Yemen
ReutersThe Saudi Crown Prince has taken out adverts in the Guardian and Financial Times newspaper as he seeks to promote his image as a moderniser.
The Saudi foreign minister, Adel Al Jubeir, has responded to the massive protests, claiming they are based on a "misunderstanding" of his country's military aggression against Yemen, the poorest Arab country. Saudi Ambassador to the United Kingdom said his country cannot modernize its economy without support from the West. The big deal will, however, not be announced - namely, the potential listing on the London Stock Exchange of the state oil company Saudi Aramco, which may or may not happen.
The Prime Minister is said to have touched on the conflict and humanitarian crisis when she met with Mohammed bin Salman - who raised eyebrows for a widespread advertising campaign to mark his visit.
However, it is a dialogue complicated by the facts that MbS is personally behind the Saudi war effort and Britain has supplied much of the arms. He will be coming fresh from a visit to Egypt, where, in addition to political leaders and Muslim religious figures, he visited the Coptic Pope and invited the community to come to Saudi Arabia.
Demonstrators are protesting against Britain for licensing 4.6 billion pounds of weapons sales to Saudi Arabia since 2015.
"Arms sales may have been promoted by successive governments, but poll after poll has shown they are opposed by the vast majority of people in the United Kingdom".