Bookmaker Ladbrokes said Brexit betting markets were “in chaos” in the wake of the Government’s stunning defeat in the High Court.

The Brexit court challenge, brought by campaigner Gina Miller, means the Government cannot trigger Article 50 of the Lisbon Treaty, kicking off the EU exit process, without first winning a parliamentary vote. There will be an appeal.

The bookie still makes 2017 the odds-on 2-7 favourite for the date of the trigger, but it has drifted out from as low as 1-5.

Betfair’s exchange – where the odds are set by punters betting against each other – also showed a significant move.

It has matched £5,929 at as low as 1.15 – paying just 15p on the pound – on Brexit starting before July 2017. There was money available to match at 1.42 at the time of writing.

Prime Minister Theresa May had pledged to trigger Article 50 before the end of March next year but the exchange’s market on it not being triggered before July 2017 has come in dramatically.

Bets had been matched at as high as 10-1, but the best price at the time of writing was just 2.6-1.

Ladbrokes’s odds on Brexit not happening before 2021, or at all, have collapsed into 2-1. The bookmaker had originally offered 5-1 leaving some punters sitting pretty and able to close out their bets at substantial profits.

The odds of an early general election in 2017 have also been cut to 2-1, although 2020 remains the odds-on favourite. But the Betfair exchange now has 2017 as favourite. It’s available to back at a little better than evens.

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For an early poll to happen the Government would have to either find a way around the fixed term parliaments act, or repeal it.

But it could be an option if the political crisis triggered by the court decision deepens.