Theresa May will ramp up planning for a no-deal Brexit after Cabinet ministers agreed to make it an “operational priority” for the Government.

The Prime Minister’s Brexit deal remains the preferred outcome for the Government but with just over 100 days until the UK’s departure from the bloc the intensity of preparations for crashing out in March 2019 will increase.

Brexit Secretary Steve Barclay stressed that unless MPs back Mrs May’s deal when it returns to the Commons in January the default option is for the UK to leave without any exit arrangement in place.

Some 3,500 troops will be on stand-by to help deal with the impact of a no-deal Brexit, it emerged.

Brexit Secretary Stephen Barclay said no-deal planning was now an 'operational priority' (Kirsty O'Connor/PA)
Brexit Secretary Stephen Barclay said no-deal planning was now an ‘operational priority’ (Kirsty O’Connor/PA)

Speaking after the Cabinet agreed to step up no-deal preparation, Mr Barclay said: “Parliament needs to back the deal because the consequence of not doing so is we risk the default of no-deal and a responsible government must prepare for that eventuality.

“That is what we agreed at Cabinet. That is what we are going to do.”

He dismissed alternative plans being pushed by ministers – including a second referendum or a “managed” no-deal under which arrangements are made with Brussels to limit any negative impacts of severing ties with the EU.

“There are a number of scenarios being floated in government without, I think, people really engaging on the consequences of that – either the consequence to our democracy of not delivering on the referendum, not having Brexit – or the idea that we can cherry-pick and have some managed no-deal where the EU will suspend its own red lines, which I don’t think is feasible.”

In a direct plea to the UK’s business community he urged company bosses to make sure they were ready for a no-deal Brexit.

It needs to be “much more of a priority for businesses up and down the country”.

In the Commons, Mr Williamson said the Ministry of Defence had not had a “formal request” for support in no-deal Brexit planning but “what we will do is have 3,500 service personnel held at readiness – including regulars and reserves – in order to support any Government department on any contingencies they may need”.