The Brexit negotiations are reaching a crucial phase for all the key political players this is the endgame. There have also recently been a slew of job losses and closure announcements from major manufacturers like Honda, Nissan and Ford, each making it clear that this is not just “project fear”, this is a succession of real-time events that we actually need to be frightened of.

Outside of peace and war, discussions surrounding Brexit hardly get more serious than this. So it is extremely important that political leaders are honest in this debate. How else can the public make informed judgements? Sadly, that task is becoming increasingly difficult, as the prime minister has got into the habit of telling half-truths and complete untruths about Brexit.

Theresa May has posed false choices of “my deal or no deal”. She repeats the same misleading statements such as “there are substantive discussions with the EU on the backstop”. And she has resorted to complete distortion on the crucial matter of the customs union.

Car manufacturers cutting UK jobs Show all 5 1 /5 Car manufacturers cutting UK jobs Car manufacturers cutting UK jobs Jaguar Land Rover Britain's largest automotive manufacturer announced in January that it plans to cut 4500 jobs from its 40,000 workforce Getty Car manufacturers cutting UK jobs Nissan The Japanese car company announced early in February that it would no longer be making the new X-trail model at its Sunderland factory Getty Car manufacturers cutting UK jobs Honda Honda has announced that it is planning to close its Swindon plant with the loss of 3,500 jobs PA Car manufacturers cutting UK jobs Michelin Michelin announced in November that it will close its Dundee tyre factory which employs over 800 people by 2020 PA Car manufacturers cutting UK jobs Schaeffler Shchaeffler's Llanelli plant is to close by the end of 2019. The company provides automotive and and industrial parts worldwide and the Llanelli plant employs over 200 people. Juergen Ziegler, chief executive for Europe, said that while Brexit was not the only factor, it has "brought forward" the decision to relocate Google

In her recent letter to the Labour leader Jeremy Corbyn, the prime minister berated him for his consistent demand for membership of a customs union. And it is worth mentioning that it is a request which has the support of both business and trade unions. In the response to the Labour leader’s demands, the prime minister wrote: “As I explained when we met, the political declaration explicitly provides for the benefits of a customs union – no tariffs, fees, charges or quantitative restrictions across all sectors and no checks on rules of origin (paragraph 23).”

This would be reassuring if it were true. The prime minister has misquoted the political declaration, and the misquotation helps her argument.

Here is the aforementioned paragraph 23 of the political declaration in full: “The economic partnership should ensure no tariffs, fees, charges or quantitative restrictions across all sectors, with ambitious customs arrangements that, in line with the parties’ objectives and principles above, build and improve on the single customs territory provided for in the withdrawal agreement which obviates the need for checks on rules of origin.”

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The prime minister is effectively claiming that the political declaration “provides for the benefits” of a customs union when it does nothing of the sort. Looking at paragraph 23 in its entirety, it’s clear that this is, at best, May’s hope that the political declaration is as explicit as she suggests when it comes to membership of a customs union, not a gurantee. “Should” is the crucial word here.

It is an aspiration, and not something that will necessarily follow at all. It is also accompanied (for example in paragraph 26 of the declaration) by all sorts of wishes based for “facilitative arrangements and technologies” which have so far proved elusive if not illusory in relation to the backstop in Ireland.

Words matter. They particularly matter in treaties and political declarations. The withdrawal agreement, widely known as “May’s deal”, clearly sets out the objective of leaving both the customs union and the single market. Leaving them both is part of the prime minister’s many red lines.

Not only are May’s claims on the political declaration false, they are an attempt to obscure the decisive difference between her deal and Corbyn’s policy.

Corbyn is demanding that our economy is in a customs union with the closest possible relationship with the single market. The prime minister is willing to destroy tens of thousands of jobs and lower living standards as workers at Nissan, Ford and Honda are finding out. And the distortion of the truth is part and parcel of that plan.