Andrea Leadsom has confirmed she is quitting the race to succeed David Cameron, saying a nine-week leadership campaign at such a critical time for the UK would be 'highly undesirable' - paving the way for Theresa May to become the next Prime Minister.

Announcing her desicion, Mrs Leadson said: "So this morning I have written a letter to Graham Brady, the chairman of the 1922 Committee, and I would like to read it out to you.

"The best interests of our country inspired me to stand for the leadership. I believe that in leaving the EU a bright future awaits, where all our people can share in a new prosperity, freedom and democracy.

"The referendum result demonstrated a clear desire for change - strong leadership is needed urgently to begin the work of withdrawing from the European Union.

"A nine-week leadership campaign at such a critical moment for our country is highly undesirable."

Graham Brady, the chairman of the Tory backbench 1922 Committee, then made a statement about the leadership contest on the steps of St Stephen's Entrance to Parliament.

He said Theresa May will be formally confirmed as the new party leader as soon as the Conservative Party board has been consulted, although he refused to give an exact timetable.

News of Mrs Leadsom's planned statement came moments after Mrs May launched her national campaign with a speech in Birmingham in which she presented herself as the candidate of unity and experience, with the backing of an "overwhelming" majority of Tory MPs at Westminster.

The Home Secretary took top slot in the MPs' ballot last week with 199 votes to her rival's 84.

And Mrs Leadsom's campaign got off to a disastrous start after she was forced to apologise to Mrs May for a newspaper interview in which she appeared to suggest that being a mother gave her an edge over the childless Home Secretary as a future prime minister.

The energy minister - who entered Parliament in 2010 and has never held a Cabinet post - admitted that she had been "shattered" by the experience of intensive media scrutiny, which also involved questions about apparent inaccuracies on her CV and demands for her to publish her tax returns.

Mrs May left the venue of her campaign launch speech in Birmingham before reporters there were able to ask her about Mrs Leadsom's statement.