LONDON, ENGLAND - MARCH 08: Theresa May leaves for Prime Minister's questions ahead of the 2017 Budget at 10 Downing Street on March 8, 2017 in London, England. Today's Budget will be the last one to take place in the spring. It is being replaced by an annual autumn Budget, the first of which is to be held later this year. The current Chancellor wants to simplify the process of setting taxes and government spending. (Photo by Dan Kitwood/Getty Images)

LONDON, ENGLAND - MARCH 08:  Theresa May leaves for Prime Minister's questions ahead of the 2017 Budget at 10 Downing Street on March 8, 2017 in London, England. Today's Budget will be the last one to take place in the spring. It is being replaced by an annual autumn Budget, the first of which is to be held later this year. The current Chancellor wants to simplify the process of setting taxes and government spending.  (Photo by Dan Kitwood/Getty Images)

2LONDON, ENGLAND - MARCH 08: Theresa May leaves for Prime Minister's questions ahead of the 2017 Budget at 10 Downing Street on March 8, 2017 in London, England. Today's Budget will be the last one to take place in the spring. It is being replaced by an annual autumn Budget, the first of which is to be held later this year. The current Chancellor wants to simplify the process of setting taxes and government spending. (Photo by Leon Neal/Getty Images)

2LONDON, ENGLAND - MARCH 08:  Theresa May leaves for Prime Minister's questions ahead of the 2017 Budget at 10 Downing Street on March 8, 2017 in London, England. Today's Budget will be the last one to take place in the spring. It is being replaced by an annual autumn Budget, the first of which is to be held later this year. The current Chancellor wants to simplify the process of setting taxes and government spending.  (Photo by Leon Neal/Getty Images)