Claire Trevett: PM Jacinda Ardern one of the Commonwealth newbies, but no pushover

Britain's Prince Charles poses for a photograph with Prime Minister Jacinda Ardern in Clarence House, London, following a bilateral meeting yesterday. Photo / AP

On London's streets, the presence of more than 50 leaders in the country equals even more chaos than normal.

The blocks around Buckingham Palace where the Commonwealth Heads of Government meeting are being held are closed to traffic and a haven of peace, but just outside police spent hours trying to shoehorn motorcades through the traffic, forcing cars up onto roundabouts around Trafalgar Square to squeeze them through.

British PM Theresa May greets Prime Minister Jacinda Ardern on the doorstep of 10 Downing St. Photo / AP

Among them is Jacinda Ardern who is at her first Commonwealth Heads of Government Meeting and finding herself in all manner of contrary positions.

Last night she was a republican in a royal palace - meeting the Queen. The day before it was Clarence House to meet Prince Charles.

Even monarchist former PM John Key believes New Zealand might look at a change once the Queen's throne is passed on and Ardern holds a similar view.

Those royals need not fear Ardern will make any sudden lurches towards republicanism.

Her first day in London began in like-minded company with London's Mayor Sadiq Khan and Canada's PM Justin Trudeau. Both are what Ardern and they like to call "progressives" - the apparently more user friendly word for lefties.

Australian PM Malcolm Turnbull, left, Canadian PM Justin Trudeau and British PM Theresa May with Prime Minister Jacinda Ardern at the National Cyber Security Center in London yesterday. Photo / AP

But as the so-called "family photo" of the leaders illustrates, such summits necessitate mixing with people of all political shapes and sizes.

When it comes to traditional allies, the left and right divide has not really mattered for New Zealand,

Ardern calls Australia's PM Malcolm Turnbull and British PM Theresa May by their first names.

But the difference between them was clear at the Five Eyes meeting later that night when Ardern and Trudeau met with May and Australia's PM Malcolm Turnbull - both conservatives who are less queasy about military action.

The difference in their opening statements was stark. May and Turnbull both hauled out strong language to lambast Russia over the use of nerve agent in Salisbury and cyber attacks. Both spoke strongly about the need for the missile attacks on Syria by the UK, France and US.

Prime Minister Jacinda Ardern and partner Clarke Gayford pose for a photograph with Britain's Prince Charles and Camilla Duchess of Cornwall in London. Photo / AP

Turnbull issued a reprise of the former Prime Minister Michael Joseph Savage's old wartime saying about Britain and her colonies: "where she goes, we go"

"We responded with the solidarity we've always shown when Britain's freedoms have been challenged."

Ardern might be the leader of the same party as Savage but she was the only one of the four who did not did not even mention Salisbury - something of a lapse in May's presence.

Ardern did not mention Russia. Nor would Ardern budge in her stance on the missile attacks on Syria which she has said New Zealand "accepts" rather than "supports". She said a message needed to be sent and had now been sent - but next should be the UN - not more unilateral action.

Ardern might have been the newest leader on the block but she showed she was no pushover when it came to proving New Zealand had an "independent" foreign policy.