The SNP’s controversial plans to assign every child a ‘state guardian’ have descended into chaos again after a cross-party Holyrood inquiry concluded that it could not recommend that MSPs give their approval.

The Scottish Parliament’s education committee said it was impossible to scrutinise how the Named Person scheme would work in practice until John Swinney, the SNP Education Minister, provides an “authoritative” code of practice for those filling the role.

In a move that threatens to delay its implementation by at least six months, its members said the code should reflect changes in data protection law being made by the UK Government in April or May next year.

James Dornan, the committee’s SNP convener, wrote to Mr Swinney requesting that the parliamentary timetable for the Named Person legislation be extended so a new code can be drawn up and scrutinised.

The Tories and campaigners said the rebuff was a “damning indictment” and urged him to scrap the plans. Even Labour, which has consistently supported the scheme, questioned whether it was “saveable” following the latest setback.

Mr Swinney has already put the plan on hold and dramatically water down its information-sharing powers after the UK Supreme Court ruled that it breached parents' human rights, confidentiality laws and data protection.