Lord Lisvane said a tactical delay "would be extraordinarily contentious, and would be open to the strongest criticism" | U.K. Parliament Former UK parliament adviser warns legal loophole could lead to no-deal Brexit Former Commons Clerk Lord Lisvane issues a note of caution to Boris Johnson.

LONDON — Boris Johnson could shut down parliament after a vote of no confidence to prevent MPs blocking a no-deal Brexit, a former House of Commons clerk has warned.

Robert Rogers, now Lord Lisvane, who served as the most senior constitutional adviser to the House between 2011 and 2014, was scathing about the reported plans by Johnson to ignore a vote of no confidence and delay an election until after the Brexit date.

He said that while it would be possible to suspend the Commons through a "Sittings of the House Motion" to force a no-deal departure from the EU, the tactic would be an “open subversion” of the laws governing parliamentary terms, and “constitutionally destructive.”

Downing Street has refused to rule out the prospect of Johnson ignoring a no-confidence vote aimed at stopping a no-deal Brexit.

Under the Fixed Term Parliament Act (FTPA), MPs would have 14 days after a no-confidence vote to pass a vote of confidence either in the existing government or a newly formed one, otherwise a general election would be triggered.

It means a prospective successor to the prime minister would need to have formed a government at the request of the queen before a second confidence vote is held.

The government could move a “Sittings of the House Motion” in an effort to keep the House from sitting and passing a motion in support of a new government.

MPs who want to prevent a no-deal Brexit have been discussing whether a cross-party government of national unity could be formed to seize power and block a no-deal departure from the EU by extending the Article 50 negotiating period.

But Lord Lisvane said the idea would bring the queen “uncomfortably close to the political mechanics.”

“Involvement of the Monarch in this way must be avoided,” he wrote in an explanation to POLITICO. “What would be infinitely preferable would be for there to have been a motion ... which demonstrates that an alternative grouping can command the confidence of the House.” If such a motion passed, the queen could then "confidently" ask the leader of that group to form a new government.

But he warned that the government could also move a “Sittings of the House Motion” in an effort to keep the House from sitting and passing a motion in support of a new government.

“To do so would be an open subversion of the (admittedly unsatisfactory) FTPA process, and would be open to fierce (and justified) criticism on the grounds that it would prevent the House of Commons coming to a view which might be supportive [of] an alternative PM,” Lord Lisvane said.

The peer argued an amendment MPs tacked on to the Northern Ireland bill, which requires the Commons to debate regularly as long as Stormont is not reformed, would do little or nothing to solve the issue.

A separate constitutional expert, who spoke to POLITICO on condition of anonymity, said any attempt to stop MPs sitting during the 14 days would “imply the Government thinks there is someone else who could command the confidence of the Commons.”

The expert said this would amount to a "constitutional crisis" in which "the most basic of democratic norms" was being violated, pushing MPs to find an “extra-parliamentary” way to communicate that they want to install a specific new prime minister.

The expert said one way to avoid the issue could be to amend the original motion of no confidence, spelling out who should take over as a successor prime minister.

Such a move would not come under the FTPA and would not trigger the 14 day countdown to an election, but would force Johnson to resign under constitutional convention, they argued.

Lord Lisvane said a tactical delay “would be extraordinarily contentious, and would be open to the strongest criticism on the grounds that (1) it was an abuse of the power conferred by the FTPA and (2) that it brought The Queen into that contention.”

He added: “In constitutional terms both would be highly undesirable and constitutionally destructive.”