The British government has encountered a roadblock in its efforts to quit the European Union following a High Court verdict determining that the UK parliament needs to be consulted over any plans to trigger Article 50.

Prime minister Theresa May had previously stated that her intention to begin the formal process of leaving the EU by the end of March 2017 at the latest, but this timetable has been thrown into doubt following a successful legal case brought against the government by investment manager Gina Miller.

Mrs May's plan was to activate Article 50 without first putting it to a parliamentary vote, as she argued that the June Brexit referendum that resulted in a vote to leave the bloc had been ratified by parliament, meaning they did not need to be consulted again.

However, the High Court has decided that quitting the EU will have too many effects on the personal rights of British citizens for such a step to be taken without further parliamentary review and approval, arguing that to do otherwise would undermine the sovereignty of the British parliament.

This could create problems for Mrs May's Brexit strategy, as she may now need to reveal details of her negotiating position earlier than intended. MPs will also have an opportunity to argue against any moves towards a so-called "hard Brexit" that would completely sever ties with the European single market in order to regain control of immigration rules, at the expense of impeding free trade with the remaining EU nations.

The value of the British pound surged to a four-week high on the back of this news, but the government has confirmed that it will be launching a Supreme Court appeal against the ruling, while Mrs May is set to tell European Commission president Jean-Claude Juncker that she considers her original Brexit timetable to be on track despite the decision.