Anti-monarchy campaigners have called for a wide-ranging review of Britain's constitution, following claims Theresa May could use the Queen to block parliament's will.

Campaign group Republic has said the shambolic Brexit process has exposed the truth behind the monarchy: that it serves no purpose but to do the PM's bidding.

Republic is calling for the Queen to be replaced by an effective, independent, elected Head of State.

Graham Smith, speaking for Republic, said today:

"Brexit has shown how the monarch offers no leadership, no independent voice at a time of crisis. And the suggestion the PM may tell the Queen to block a parliamentary bill exposes the truth behind the monarchy."

"The monarch isn't independent, she is there to do the government's bidding, to do as the PM tells her to do."

"Britain is witnessing a clash between the fiction of parliamentary democracy and the reality of constitutional monarchy.  In the UK the Crown holds significant power, power exercised on the instruction of the government."

"Britain needs to establish clear boundaries between the power of the government, parliament and head of state.  And if the head of state is to play any role at all, they must be accountable."

"Ireland does this well, as do other European countries.  The UK is quite capable of electing some to the role of head of state, not to run the country but to exercise constitutional authority."

"Recent reports that lawyers are accusing parliament of abusing constitutional process, and advocating the Queen take action against our elected MPs should sound alarm bells.  Our constitutional monarchy is failing us.  We need reform and we need it sooner rather than later."