On a visit to Edinburgh, the Cabinet Office minister said Theresa May took the view that it could not be left to civil servants to sort out the customs row, which has split her Cabinet.
Mrs May has asked two teams to three ministers to look at two customs options – a customs partnership and the so-called “max-fac” option.
Mr Lidington, along with Liam Fox and Michael Gove, is a member of the team looking at the customs partnership option – a potential solution that has been dismissed as “crazy” by Boris Johnson.
Business Secretary Greg Clark, Brexit Secretary David Davis and Northern Ireland Secretary Karen Bradley will look at max-fac. Max fac or maximum facilitation accepts the need for a customs border, including in Ireland, and depends on the development of technology to make it as frictionless as possible.
Mr Lidington acknowledged there had been internal criticisms of both models.
“The Prime Minister was very clear we needed to have hands on involvement by ministers,” Mr Lidington said. “It wasn’t going to be enough to ask our civil servants to come back with another paper and have a discussion about that.”