Commonwealth leaders - among them Prime Minister Jacinda Ardern - have returned from a London retreat with a new sense of purpose for the 53 nations. But how realistic are their ambitions?

On day one in London, as Kiwi reporters set up shop at the media centre alongside Marlborough House - once a royal residence, now home to the Commonwealth Secretariat - we have our first brush with British comedy.

An official, arms waving, swoops in to usher us to another table - apparently we've inadvertently encroached on the designated QUIET AREA, one corner of the enormous room plainly set aside for stillness and solitude.

Photo: RNZ Insight/ Craig McCulloch

Hanging above the meditation zone, loudspeakers broadcast the day's proceedings at full volume, periodically detailing the cafeteria's menu. An endless procession of journalists - no doubt in deep introspection - traipse in and out of the nearby entrance. Serene.

We move one table over to what we can only assume is the ROWDY AREA.

The encounter is indicative of many of the criticisms of the Commonwealth: a bit stuffy, archaic, ultimately pointless.

Leaders this year were in desperate search of a purpose. British Prime Minister Theresa May talked of an "incredible opportunity". Prince Charles prayed the Commonwealth would be imbued with "renewed relevance". The Queen tried her best to look engaged.

One after another, each country's leader added his or her voice to the drone, repeating the event's constant mantra: "Towards a Common Future".

Even Prime Minister Jacinda Ardern joined in, as she raised a toast at the state banquet at Buckingham Palace.

"To the Commonwealth," she said. "Towards a Common Future."

The glasses clinked - and the guests panicked, unsure whether to repeat the first refrain or the second. So much for unity.

Photo: Supplied - Pool

For the many hopeful, the Commonwealth's future lies in the ashes of Britain's relationship with the European Union. The theory goes that as the United Kingdom turns its back on the EU, it will embrace its old friends and former colonies.

Back home, Winston Peters has long championed the idea, well before becoming deputy prime minister and foreign minister last year.

In May 2016, the NZ First leader addressed the British House of Lords and - in typically understated fashion - implored the UK to take a "bold and courageous step back to the Commonwealth", signalling the "dawn of a new age".

After keeping a low profile during this year's CHOGM, he suddenly popped up at the week's end, full of zeal but in need of a thesaurus.

The meeting was "exciting", he said, the possibilities "exciting and new" and along "exciting lines"; there was "energy and urgency" and "a whole lot of excitement".

The big idea - which has him ebullient, enthused and effusive - is a Commonwealth Free Trade Area.

Photo: Supplied - Pool

Mr Peters said leaders from the Commonwealth nations were keen to develop a framework for a group-wide agreement.

But will that ever happen?

Sir Don McKinnon, a former deputy prime minister of New Zealand and former secretary-general of the Commonwealth, said the 53 countries were just too different.

"To try arrange that between all the African nations - and then the Caribbean nations - and the South Asian nations... it would be asking what could probably not be delivered that easily."

But Stephen Jacobi, who is the executive director of the New Zealand International Business Forum, said it was too soon to tell.

"Who knows where such discussions in the Commonwealth might lead - the important thing is to not close off options before they have been properly explored."

Sir Simon Fraser, a UK business adviser and former chief civil servant of the UK Foreign Office, said it was a very diverse group of countries with diverse interests.

"There isn't a sufficient unity of interest for there to be something called a Commonwealth bloc or Commonwealth area."

While Charles Finny, a New Zealand trade expert and former diplomat, said to give it time.

"I can recall people saying we were crazy thinking about a free trade agreement with China, with Taiwan... so these things, if you give them time, may lead to exciting outcomes."

And Linda Yueh, a Royal Commonwealth Society trustee, said completing a free trade agreement was a very difficult task.

"The EU is the example with the most countries in it - and when it was originally devised there were less than a dozen countries."

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Whatever the prospect of a Commonwealth-wide trade deal, it won't be any time soon.

Both Ms Ardern and Trade Minister David Parker acknowledge such an arrangement would take a long time and doesn't sit high on New Zealand's list of priorities.

And so the Commonwealth waits - more hopeful than ever, but still so uncertain.

At Buckingham Palace, a Commonwealth chorus performs that dignified and stately song, Unwritten, the theme to reality TV show The Hills.

Natasha Bedingfield's lyrics go: "I'm just beginning... ending unplanned".

As the song comes to a close, one of the six singers - in a flamboyant finish - loses her footing and stumbles, the crowd joining her with peals of laughter.

The Queen doesn't crack a smile.

Photo: Supplied - Pool

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