Boris Johnson has said that the UK could stay in the customs union and single market for another two years, as he appeared to suggest what a Brexit deal struck by his Government could look like.

The Prime Minister described the chance of a no-deal Brexit as “vanishingly small” as he visited farmers in Wales on his tour of the UK.

However, he stressed that the cost of no-deal preparations - such as building new customs facilities - will not be a “wasted effort” even if the UK manages to agree a deal with the European Union.

He said: “Some of the changes and adjustments necessary in the run-up to October 31, and a lot of which we have already done, will be crucial anyway if we are going to come out of the customs union, come out of the single market as we must in the next couple of years.”

Mr Johnson was describing a scenario in which the UK manages to strike a new deal before Hallowe'en, which would see Britain then enter a transition period before a free trade agreement is reached.

Under the putative plan, the existing one-year "transition period" in the Withdrawal Agreement would be extended by up to a year to allow a free trade deal to be negotiated, but there would be no backstop after this period. This could involve an additional payment to Brussels.