Opponents of the Northern Ireland Protocol have been dealt a blow after the High Court threw out a bid for the Brexit deal to be declared unlawful.

       Unionist leaders launched the legal challenge in protest at the agreement – signed by Boris Johnson and the EU – creating a trade border in the Irish Sea, disrupting supplies.

       But a judge in the Belfast court ruled that the EU Withdrawal Act overrides claims that the Protocol breaches the Acts of Union between Britain and Ireland.

       The challenge was brought by leading Unionists including Arlene Foster, the former DUP leader, and David Trimble, an architect of the Good Friday Agreement.

       They argued that the Protocol breaches Article 6 of the Acts of Union which created the United Kingdom of Great Britain and Ireland in 1800, by leaving Northern Ireland inside the EU’s customs union.

       Recommended UK weather: The latest Met Office forecast UK to agree to ‘conditions’ with EU as both sides prepare truce to avoid ‘sausage war’ Study nixes life in clouds of Venus, but maybe in Jupiter's?

       It was also claimed that the agreement ran contrary to the Northern Ireland Act, the legislation which brought the 1998 Good Friday Agreement into law.

       But Mr Justice Colton refused a judicial review, pointing out that “much constitutional water has passed under the bridge” since the year 1800.

       However – in what is certain to be a provocative mood – he agreed the Withdrawal Act does conflict with the 1800 Act, but ruled it overrode the provisions of the 200-year-old law.

       A government lawyer had told the High Court that the Northern Ireland Protocol is an “orthodox application of parliamentary sovereignty”.

       The applicants were effectively “asking the court to ignore the will of parliament expressed in primary legislation”, it was argued.

       Furthermore, the government insisted that Northern Ireland remains within the UK’s custom territory – despite the trade checks introduced – which meant there is no breach of the Acts of Union.

       The ruling comes as tensions continue to rise over the new trade border, with Unionists accusing the prime minister of betrayal – and of dishonesty in claiming its impact was not fully anticipated.

       The EU and UK are poised to agree a truce to delay a looming ban on the sale of chilled meats from Britain and to ensure new medicines are available in Northern Ireland.

       But the government has refused to scrap or suspend the Protocol – despite repeatedly threatening to – preferring to work with Brussels to try to make changes.

       An opinion poll by researchers at Queen’s University Belfast has found people in Northern Ireland are “evenly split” over the Protocol.

       However, recent protests have “not led to any significant growth in the proportion of voters objecting to it”, suggesting that positions on the Protocol are “already quite well entrenched”.

       When asked whether the Protocol is appropriate for Northern Ireland, 47 per cent agrees that it is, but 47 per cent disagreed.