Prime Minister Malcolm Turnbull has taken a shot at critics on the right of his party, saying the Liberals' founder Sir Robert Menzies never intended his party to be conservative.

Key points: Malcolm Turnbull says Sir Robert Menzies — the longest-serving Liberal leader — purposely avoided calling the party "conservative"

Malcolm Turnbull says Sir Robert Menzies — the longest-serving Liberal leader — purposely avoided calling the party "conservative" Comments come in the wake of criticism from conservative Coalition backbenchers, including former PM Tony Abbott

Comments come in the wake of criticism from conservative Coalition backbenchers, including former PM Tony Abbott Mr Turnbull was speaking in London where he was receiving the Disraeli Prize

The comments were part of a speech delivered in London overnight where Mr Turnbull was receiving the Disraeli Prize awarded by UK think tank Policy Exchange.

In his speech, the Prime Minister made the case that his party's longest serving leader Sir Robert wanted to create a progressive party not a conservative one.

"In 1944 Menzies went to great pains not to call his new political party, consolidating the centre right of Australian politics, conservative, but rather the Liberal Party, which he firmly anchored in the centre of Australian politics," he said.

"He wanted to stand apart from the big money, business establishment politics of traditional conservative parties of the right, as well as from the socialist tradition of the Australian Labour Party, the political wing of the union movement.

"Menzies said at the time: 'We took the name 'Liberal' because we were determined to be a progressive party, willing to make experiments, in no sense reactionary but believing in the individual, his right and his enterprise, and rejecting the socialist panacea'."

"The sensible centre was the place to be. It remains the place to be."

The comments will be read as a rebuke to those conservatives on the backbench, led by Tony Abbott, who have been openly critical of the direction that the Government has been heading in.

Turnbull has sent 'very strong message', Bernardi says

Senator Cory Bernadi, who quit the Liberals earlier this year to form the Australian Conservatives party, said Mr Turnbull's speech had sent a "very strong message" to conservatives.

"You're no longer welcome within the party of Menzies and I suspect if Sir Robert Menzies was alive today he would be considering an alternative, because the party that he founded no longer seems to represent the interests upon which it was founded," he said.

"If a group of people are no longer welcome in their traditional home they need to find another political home, and the Australian Conservatives is designed to provide a voice, a stronger voice, a more united voice for conservatives just like Sir Robert Menzies did back in the 1940s."

Malcolm Turnbull said he and Theresa May had struggled to hold back tears at the scene of the Borough Market terrorist attack. ( AAP/Fairfax: Andrew Meares )

Earlier in the day the Prime Minister, along with British Prime Minister Theresa May made an emotional trip to Borough market where eight people, including two Australians, were killed during a terrorist attack last month.

"The three of us did our best not to burst into tears," he said.

Near Southwark Cathedral he spoke to two of the police who had tried to revive one of the Australian women who died during the attack.

"They are very brave men, very brave men and women," he said.

After meeting with Ms May to discuss trade and security, Mr Turnbull said Australia was ready to secure a free trade deal with a post-Brexit UK.

Speaking to reporters after the meeting, Mr Turnbull said a new trade deal would happen "as soon as possible, if we move quickly", after Brexit.

Ms May said securing a free trade deal between the UK and Australia remained a priority of her Government.

"We've both made clear our intention to continue to deepen our trade and investment relationship as the UK leaves the EU," she said.

Ms May said the UK and Australia were "investors in each other's success" and their growing trade relationship was worth close to $18 billion.

Mr Turnbull also said he would not accept a nuclear-armed North Korea, and has been encouraging China to put economic pressure on Pyongyang.

"The Chinese, in practical terms, is the only country that has the ability to bring the North Korean regime to its senses without some form of military intervention," he said.

"They have the ability to impose huge economic pressure on North Korea."

Mr Turnbull will also meet with Queen Elizabeth II during his visit.