Concern remains in the United Kingdom over the way in which Parliament is going about Brexit.

LISTEN ABOVE: Brexit legal campaigner Gina Miller spoke to Rachel Smalley on the Mike Hosking Breakfast

Prime Minister Theresa May has this morning outlined her plan to exit the European Union, saying Britain will leave the single market.

However Westminster is still awaiting a Supreme Court ruling about whether it can go through with Brexit, without Parliamentary approval.

Lawyer behind the action Gina Miller told Rachel Smalley using an ancient royal prerogative to trigger Brexit, is turning the clock back hundreds of years in constitutional law terms.

"Because the precedent would have been set that any Prime Minister and her executive, any in the future, could simply decide in a closed room what rights we have as citizens and what we don't so it's much more fundamental than just Brexit."

It's unlikely Britain's Parliament will try to stop the country from leaving the European Union.

British High Commissioner to New Zealand Jonathan Sinclair told Rachel Smalley it's clear from May's speech that Britain might be leaving the EU, but it still wants to be considered part of Europe.

"We want to stay the best possible friends on trade and security with our friends in Europe."

UK Correspondent Gavin Grey told Bernadine Oliver-Kerby it's possible there'll be some amendments to the final plan.

"Sources are basically say that they consider it unlikely MPs will vote against a Brexit. They do not want to be seen as a people who voted against what their constituents wanted."

Grey said Brexiteers are delighted.

"I think, at last, they are having more confidence that what they wanted is now going to happen."