AS we know, there are no straight lines when it comes to Brexit.

Superficially, for those opposed to a no-deal outcome, it might appear a no-brainer to back a Commons vote to bring down the Johnson government, install Jeremy Corbyn in No 10 for a wee while, seek another EU extension to leaving the bloc and then hold a snap general election.

Nicola Sturgeon’s SNP tentatively warmed to the idea as did the Greens and Plaid Cymru. But Jo Swinson for the Liberal Democrats branded the Corbyn caretaker plan “a nonsense,” claiming the Labour leader could hardly guarantee getting all of his own MPs to help put him in Downing St let alone Tory rebels.

While some Labourites decried Ms Swinson’s stance, suggesting it revealed the Lib Dems’ preference for putting their hatred of Mr Corbyn ahead of their commitment to stopping a no-deal outcome, others dismissed their leader’s plan as “bonkers,” noting how his commitment to holding a second referendum following a snap election would go down like a lead balloon in Leave-voting Labour constituencies.

Tory Remainers Dominic Grieve, Oliver Letwin and Nick Boles appeared open to at least having a chat with the chief comrade but Caroline Spelman, appeared positively frosty, declaring: "I could not support a Corbyn Government, end of.”

So, it may be a “no-deal alliance” might be cobbled together to bring down a Johnson government but there will not be the numbers to install Mr Corbyn in Downing St when you consider Labour Leave rebels, ex-Labour rebels who are now Independents, and Tory Remainers, who could not bear seeing the Leader of the Opposition in power however short his tenure.

So the Lib Dem leader is suggesting either Ken Clarke or Harriet Harman, the respective Father and Mother of the Commons, or indeed both, could lead an emergency unity government. Indeed, Ms Swinson told Channel 4 both were up for it.

But if no alternative government can be formed, then Mr Johnson, by law, can recommend to the Queen when a general election should be held ie after Brexit happens on October 31, meaning those backing Nigel Farage’s Brexit Party would swing behind the Tories to give them a Commons majority.

With this prospect, the pressure therefore is on the Remainers to unite in the weeks through September and October to find a way block a no-deal outcome.

In April, MPs successfully passed a Bill to get the Government to ask for an extension; one was granted until October 31. Mr Grieve believes they can repeat the exercise but there are no guarantees; even with a sympathetic Speaker.

Whitehall insiders believe the powerbrokers of Brussels will cave in at the very last moment. Yet in this Brexit psychodrama, the only certainty is uncertainty.