BORIS Johnson’s decision to prorogue Parliament for five weeks ahead of Brexit rendered proper scrutiny all but impossible and was “blatantly designed” to frustrate MPs, a court found.

A panel of three judges at the Court of Session in Edinburgh caused shockwaves on Wednesday after ruling the Prime Minister acted unlawfully by suspending Westminster.

In a full judgment, published yesterday, they set out their arguments and effectively accused Mr Johnson of misleading the Queen in advising her to prorogue Parliament.

Number 10 has repeatedly insisted the move was to bring forward a new legislative agenda.

The Lord President, Lord Carloway, Scotland’s most senior judge, said the suspension was sought in a “clandestine manner”.

He said: “The circumstances demonstrate that the true reason for the prorogation is to reduce the time available for Parliamentary scrutiny of Brexit at a time when such scrutiny would appear to be a matter of considerable importance, given the issues at stake.”

He added: “There was, and is, no practical reason for a prorogation for what is, in modern times, an extraordinary length of time (five weeks instead of about seven days).”

Lord Brodie said the move was “blatantly designed” to frustrate Parliament at a critical juncture in the history of the UK.

And Lord Drummond Young said nothing in the documents provided by the UK Government “can be said to provide any rational explanation as to why Parliament must be prorogued as early as 9 September for a period of five weeks”.

He said: “In these circumstances I have come to the conclusion that the only inference that can properly be drawn on an objective basis is that the government, and the Prime Minister in particular, wished to restrict debate in Parliament for as long as possible during the period leading up to the European Council meeting on 17-18 October and the scheduled date of Britain’s departure from the European Union.”

He added: “The effect of the prorogation under consideration, in particular its length, is that proper Parliamentary scrutiny is rendered all but impossible.”

There were gasps as the explosive ruling was read out at the Court of Session on Wednesday.

The UK Government has appealed the decision to the UK Supreme Court.

Mr Johnson faces being forced to recall Parliament if it upholds the Scottish ruling, which came after a legal challenge by a cross-party group of more than 70 MPs and peers, led by the SNP’s Joanna Cherry QC.

A similar case at the High Court in London was dismissed on the grounds that proroguing Parliament was a political decision and not a matter for the courts. It is also being appealed.