Queen Elizabeth II urged Britain to seek out the common ground and grasp the big picture, a coded plea to the political class to resolve the Brexit crisis that has shocked investors and allies alike.

With the clock ticking down to March 29, the date set in law for Brexit, the United Kingdom is in the deepest political crisis in half a century as it grapples with how, or even whether, to exit the European project it joined in 1973.

While Elizabeth, 92, did not mention Brexit explicitly in a speech to her local Women's Institute in Norfolk, the monarch said every generation faced "fresh challenges and opportunities."

"As we look for new answers in the modern age, I for one prefer the tried and tested recipes, like speaking well of each other and respecting different points of view; coming together to seek out the common ground; and never losing sight of the bigger picture," the queen said.

The comments were interpreted as a coded signal to Britain's political class. The Times' main headline read: "EndBrexit feud, Queen tells warring politicians" while the BBC said there was no doubt the monarch was sending a message.

As head of state, the queen remains neutral on politics in public and is unable to vote though ahead of the 2014 referendum on Scottish independence, she made a delicately crafted plea for Scots to think carefully about their future.