Companies have paid a “heavy price” for ministers’ refusal to consult them fully, an inquiry by MPs was told – a stance motivated by a fear of provoking concern about the trouble ahead.
The criticism came as the head of the National Audit Office (NAO) revealed that civil servants are relying on his reports to find out what is going on in their own departments.
Sir Amyas Morse also agreed there was a real risk that flights to the EU would be grounded if there is no-deal Brexit, warning the UK was relying on “goodwill” to resolve the crucial issue.
And he suggested Theresa May’s planned 21-month transition period, after departure day next March, would be too short to secure long-term arrangements – which would require the transition to be extended.
The NAO’s auditor general also dismissed claims that crashing out of the EU onto World Trade Organisation (WTO) rules would be a comfortable outcome, warning of “high friction” for traders.
And he criticised the department for transport for underestimating the risks of Brexit, saying they had “convinced themselves it is less risky than it actually is”.
Giving evidence to the Commons Brexit committee, Sir Amyas said the secrecy surrounding preparations had been “taken too far” – particularly for businesses.
He said he understood the “desire to not cause concern”, but warned: “It has carried a heavy price with it.”
The auditor added: “I think they underestimate the capability and maturity of the business community.
“They are actually very good at running their businesses. If you don’t give them a chance to plan ahead and solve the problem you put them in a very difficult position.”
On the effect of secrecy on Whitehall, Sir Amyas said: “Members of the civil service have been using our reports to find out what’s happening on Brexit.
“I don’t think that’s a good state of affairs. I’m thrilled a have a wider readership but, if you ask people to be behind what you are doing, you need to make sure they do know what the overall enterprise is and feel really well informed.”
Dominic Raab, the Brexit secretary, has not challenged industry warnings that a no-deal Brexit would bring delays at Channel ports of “45 mins for just one truck”.
And he has appeared to confirm plans for lorries to be parked for many miles along one side of the key motorway link to Dover, once referring to “contra-flow systems on the M20”.
Later, Sir Simon Fraser, former Foreign Office permanent secretary, reminded the committee that Mr Raab had claimed Brexit would but bureaucracy and regulations.
He pointed out there were already 7,000 more civil servants, preparing for EU withdrawal, with a further 16,000 planned for 2020.
“We have all been on steep learning curve since then,” Sir Simon said. “I assume that includes Mr Raab.”
The Independent has launched its #FinalSay campaign to demand that voters are given a voice on the final Brexit deal.