Boris hails London as ‘new Athens’ but warns of threats

But the mayor, who is seeking to become MP for Uxbridge and South Ruislip at next year’s general election, also believes these values are under threat from “illiberal democracy”.

Mr Johnson said he insists Londoners and Britons must guard against oppression and ignorance in order to safeguard its status.

In a lecture to be given on Thursday next week, he will say: “For all its faults, Periclean Athens marked a high point of Western civilisation – the dawn of a political culture of freedom, openness, and tolerance, intellectual experimentation and democracy.

“Two and a half thousand years later there is one city that still incarnates and upholds those values – better, perhaps than any other.”

The speech, sponsored by London-based think-tank the Legatum Institute, will examine how the experiences of democrats in the fifth century BC can help preserve London’s unique metropolitan character today.

But Mr Johnson, who read Classics at Balliol College, Oxford as a Brackenbury Scholar, will also argue that these freedoms must be defended to protect the capital from being plunged into an era of ignorance, prejudice and oppression.

Hywel Williams, who leads the Institute’s culture of prosperity programme, will introduce the lecture which is entitled Athenian Civilisation: The Glory That Endures. He said: “Boris brings imaginative flair and sense of purpose to the public life of our time – qualities that he first displayed as a student of classical culture, the foundation stone of Western civilisation.”

Mr Johnson announced his intention to return to parliament earlier this month, amid speculation that he is positioning to take over from David Cameron as Conservative leader in the future.

Mr Johnson said he hoped to “make his case” that he was the best person to represent the constituency, held by Sir John Randall with a majority of 11,000 at the last general election.

“I’m sure there will be plenty of excellent candidates and I hope very much to make my case to the association,” he said. The Conservative candidate for the seat is due to be announced on September 12.

Mr Johnson has said that if he is elected to the Commons next May he will still serve out his term as Mayor, which ends in 2016.