MSPs warned controversial named person scheme could be delayed as Supreme Court holiday looms

Read more: Health visitor vacancies 'make it harder for named person scheme to work'

A ruling is expected in the Supreme Court after challenges by the Christian Institute and other groups, who appealed after their case was dismissed by the Court of Session.

But with the judgement still to be determined, the Supreme Court will break up in two weeks' time for a summer recess for the month of August.

It puts into jeopardy the expected introduction of the Scottish Government's flagship scheme, which was due to go live on August 31.

Mr Swinney has now written to Holyrood’s Education Committee confirming that in the absence of a determination by the UK Supreme Court, he may have to delay the implementation.

In a letter to MSPs on the committee, Mr Swinney said there were now only two weeks prior to its summer recess in which the Supreme Court could hand down its judgement.

“While I still hope that this may still happen, we face the theoretical possibility that a judgement will not have been made, prior to the commencement date of 31 August,” he said.

Read more: Conservatives call for named persons scheme to be delayed amid health visitor shortage

“It would not be prudent or responsible for government to commence legislation while a decisions for m the court is still pending, as this would potentially crate confusion on both practical and legal grounds."

Campaigners against the policy welcomed the statement.

Simon Calvert, spokesman for the No to Named Persons campaign, said: "Our lawyers contacted the Scottish Government earlier this week requesting an undertaking along these lines, so we are pleased they have done the right thing.

"The fact that the Scottish Government has been forced into a concession over this unpopular scheme is an acceptance of the reality that it could actually be struck down by the Supreme Court.

"To pursue the implementation of state guardians while that prospect hangs over the scheme would indeed be inappropriate. Mr Swinney has made the right call."

Read more: Probe into named-person policy 'black-hole' being sought

Mr Swinney has previously resisted repeated calls to delay introduction of the system amid concerns about a shortage of health visitors, who along with headteachers will take on the bulk of named person duties, as well as criticism of the principle of the scheme.

The campaigners claim the law authorises “unjustified and unjustifiable state interference with family rights”. Their arguments were considered by five justices in a two-day hearing in March.

Amid the prospect of a delay in the court ruling, Mr Swinney has told MPs he is advising parliament that the relevant parts four and five of the 2014 Children and Young People Act will not be implemented until a definitive judgement is received.

“This follows usual practice and provides clarity for all concerned,” he wrote.

However, Mr Swinney insisted he remains committed to the idea of the scheme, which is intended to provide a single point of contact for accessing advice and services. Critics have labelled the policy sinister and a "big brother" style intrusion into parental rights.

Mr Swinney said: “I would wish to make clear that this contingency planning in no way undermines this Government’s commitment to the named person policy.

"I still hope that a Supreme Court judgement might be forthcoming before the court’s summer recess and that a positive judgement for the government, in line with the court hearings in Scotland, will allow the government and its partners to proceed with the implementation of this important policy.”

But Mr Calvert added: "Of course, as well as the legal problems, the scheme is plagued by practical problems.

"More than a million kids are meant to be assigned a named person but there aren’t enough health visitors or teachers to implement the scheme. That may be partly behind this concession.

"Mr Swinney has a full in-tray to cope with. But the named person scheme is probably his biggest headache and perhaps by announcing this pause he is hoping to secure time to fully review the problems which it will doubtless unleash if it ever goes ahead. We can only hope so."