Stephen Wall made the comments yesterday at an Institute for Government panel discussion on how Whitehall should approach the Brexit negotiations.
The former civil servant said: “One of the things they have needed and I think have rather turned their faces against is bringing in expertise.”
He said he was aware of at least two former colleagues whose offer of help was rejected by the government.
Wall suggested this was done on the basis of “if your face doesn’t fit, you don’t get into the room” – a position he described as “just daft”.
“I hope that the ability will be there for the civil service to do the work [to bring the UK out of the EU],” he added.
Fellow panelist, Andrew Cahn, former head of UK Trade and Investment and chef de cabinet to Lord Kinnock, agreed with Wall’s analysis.
Cahn said the government should bring in experts that understand the issues, even if they aren’t granted any power.
But he agreed there seems to be a “dogmatic philosophy”, which viewed “anybody from the past, associated with the EU, who maybe a remainer, [as] beyond the pale”.
Cahn said this was “childish” and the government needed to “get over that”.
Labour MP Gisela Stuart echoed these concerns as she noted Parliament was “void of any collective memory of anything to do with the European Union”.
She cited the lack of debate in the Commons since 2010 on fisheries, agriculture and David Cameron’s reluctance to deal with EU issues, which she said were viewed as backbench business.
Stuart said: “I am incredibly fearful that the collective memory to understand isn’t there”, adding that it was “deeply misguided” to not accept advice from people with “institutional memory” of dealing with the EU.
