Foreign Office staff have been banned from using certain words and phrases in discussing Brexit – including “implementation period”, “no deal”, “special partnership” and even Brexit itself unless in certain narrow circumstances.

The directive underlines the degree to which Downing Street is determined that everyone in the department follows its ideological lead in using language that frames Britain’s departure from the European Union as a clean break.

The memo’s opening sentence says “Brexit is completed. So do not use the term ‘Brexit’, save as a historical event that took place on 31 January 2020”. It then advises “use ‘transition period’ not ‘implementation period’.”

The directive continues: “On 31 December 2020 we will either leave the transition period with a Canada-style free trade agreement’ or the ‘2019 deal’ which will give us a trading relationship with the EU like Australia’s”.

They were told: “Do not use phrases such as ‘deal/no deal’.”

Diplomats have also been urged to stress that “the UK’s priority in the negotiations is to ensure that we restore our economic and political independence on 1 January 2021. That is the government’s primary objective. If asked to expand, we will ensure that we will have the right to regulate and are not constrained by EU law or the court of justice of the European Union.”

Other words that are frowned upon in the guidance include “ambitious”, “unique”, “deep”, “bespoke” or “anything else that can be taken to mean anything other than a typical free trade agreement of the Canada type”. It adds: “If hyperbole is absolutely essential, only make reference to a deal “at least as good as [Canada’s deal with the EU]”.

Another word now banned inside the Foreign Office is “partnership” in connection with the future relationship with Europe, still less “deep” or “special” partnership. The EU will be one of many partners. Staff are told: “Stick to the phrase ‘friendly cooperation between sovereign equals’.”

There are also some EU terms that must be avoided, the core script suggests.

The memo says: “Use ‘subsidies’, not ‘state aid’.” Staff are urged to avoid using trade distortions, and “level playing field”.

“Be specific about what you mean when talking about migration”, and gives examples such as tourism or “immigration to live or work”. It says: “Do not give the impression that we are seeking a unique or novel agreement. Stress that we are looking for a deal based on EU precedent.”

The memo continues: “Stress that we accept the following EU claims: that a free trade agreement comes with ‘friction’. That we are able to negotiate directly only with the commission (and therefore that EU member states must persuade the commission if they need particular areas of cooperation to continue).”