IT has been dubbed Westminster’s “High Noon”. But the bewildering Brexit process has thrown up a number of moments of truth and the Commons vote on Tuesday evening could be just another one.

But as Brexit Day on March 29 approaches, tensions are rising fast in Westminsterville.

By Friday there were 14 amendments to the Brexit motion; it will be up to John Bercow, the Commons Speaker, to decide which ones MPs will debate and vote on. And just to add more confusion to the already mind-numbing complexity of the parliamentary process, there are now amendments to the amendments.

Essentially, there are two main proposals.

One is to extend the Article 50 process to avoid a no-deal outcome and the other is to kill off the Irish border backstop by seeking “alternative arrangements” to avoid a hard border.

Cross-party campaigners had been planning to put one down to secure a People’s Vote but pulled it this week because they did not have the support of Jeremy Corbyn.

Indeed on Friday, Ian Lavery, the party Chairman and a close ally of the Labour leader, knocked back the hopes of those pushing for another EU vote by warning it would risk “serious damage to the relationship between many citizens and politicians at Westminster”.

Labour’s official amendment calls for a permanent customs union and a strong relationship with the EU single market with the option of legislating for a public vote ie in line with the party conference resolution.

However, three Labour MPs, including Edinburgh South’s Ian Murray, have now put amendments down to Labour’s amendment, seeking to ensure a People’s Vote takes place.

The first key amendment is the one calling for an extension to Article 50 put down by Labour’s Yvette Cooper.

This would put Brexit Day back to December 31 2019. The idea is to give the Government time to negotiate a deal. It has support not only from Labour MPs but Conservative, Liberal Democrat and SNP ones too.

What worries Whitehall about this move, unlike the others, is that it proposes new legislation to stop the clock on Brexit.

The plan is to push Ms Cooper’s new bill through the Commons in one day: February 5. However, there is a plot brewing in the Lords – where there is no mechanism to curtail a debate – to filibuster and “talk the law to death”.

Critics of the Cooper amendment smell a rat and believe delaying Brexit is just a ruse to get Britain to stay in.

Some argue only pressure will force Brussels to budge on the backstop; any delay would mean the EU27 could string things out, knowing a People’s Vote was just around the corner and the UK would vote to stay in.

The second key amendment is now one backed by the leadership of the Tory backbench 1922 committee: scrapping the backstop with “alternative arrangements” to avoid a hard border and backing the PM’s Withdrawal Agreement - subject to this change.

Crucially, it seems, the Democratic Unionists are preparing to support this change and the authors of it are hoping Theresa May and her Government will also row behind it.

Of course, whatever the Commons finally backs still has one more formidable hurdle to overcome – securing agreement from the EU27, which has insisted it will not budge.

Nothing is certain about how this showdown is going to end and who might forsake who.