Alison Munro, the chief executive of High Speed Two Ltd said: "This is a project that the country needs. The existing railway is becoming increasingly full and by the middle of the next decade parts of it will be effectively full.
"So we need to start now to plan to have that capacity in place."
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Donald Trump is to visit the UK on July 13 and hold bilateral talks with Theresa May, Britain's ambassador to the US has said.
The Football Association has announced it has received an offer to buy Wembley Stadium.
The most hotly-tipped date is July 13, following the Nato summit which the president is due to attend in Brussels on the previous days.