The future of Ofsted's wide-ranging children's services empire has been thrown into further doubt with the announcement of a parliamentary inquiry into the effectiveness of the watchdog's huge remit.
The investigation by the Commons education select committee will also look into Ofsted's general performance and effect on schools.
Fears that the inspectorate's resources are spread too thin have grown since 2007, when Ofsted took on children's social services in a merger that also brought in the Adult Learning Inspectorate and parts of the HM Inspectorate of Court Administration.
The Conservatives have already said they want Ofsted's school inspection framework "radically simplified" to focus on education, dropping wider children's welfare categories such as ensuring that schools promote healthy lifestyles.
Now MPs could take that further by considering "whether inspection of all organisations, settings and services to support children's learning and welfare is best conducted by a single inspectorate".
New committee chairman Graham Stuart, a Conservative MP, insisted that he would not prejudge the inquiry, which has been welcomed by Ofsted.
But he said: "What is certain is it has already got a very wide remit and it has also had a significant cut in its budget.
"You get a tension in children's services at local authority level, where it is certainly a challenge if you have got someone with an education background heading it up to ensure there is strategic understanding of children's services, and vice versa.
"It is not that it can't be done, but it is challenging, and concerns have been expressed before about whether there is the right skills mix at Ofsted."
Christine Gilbert, who will leave her role as Ofsted's chief inspector next year, has estimated that her expanded empire touches the lives of up to half of England's population.
But the expansion coincided with Ofsted's budget being slashed by a third, and stresses surfaced in the aftermath of the Baby P scandal in Haringey.
It emerged that a data-based inspection of Haringey Council children's services, conducted by Ofsted more than a year after Baby P's August 2007 death, had concluded that the authority was delivering a "good" service.
But less than six months later, in December 2008, a second Ofsted report delivered a damning verdict on the same council department.
John Chowcat, general secretary of Ofsted inspectors' union Aspect, argues it is still "early days" for the watchdog's wider children's role and believes it would be a mistake to abolish it now.
He also fears that the latest inquiry could prompt even lighter-touch inspections and less "rigour" from Ofsted.
"This could raise question marks when they are not needed about a system that has broadly been welcomed and is beginning to work through," he said.
Much of the inquiry's brief has already been covered by the report on schools accountability by the then Commons schools select committee in January.
The report called for Ofsted to focus less on test results and more on teaching quality and said Government should improve the quality of inspectors.
But Mr Stuart aside, the committee's composition has completely changed since the general election.
The new inquiry will also consider how Ofsted should provide accountability for schools that have been given more autonomy under ministers' expanded academies programme.
An Ofsted spokesperson said: "Ofsted welcomes the opportunity to discuss our role in raising standards for children and young people, parents and carers, employers and learners of all ages.
"People tell us they value our work in driving improvement, empowering parents and service users, and keeping children safe."
The committee is requesting written submissions by October 8.
Reach, performance, quality: a role inspected
The inquiry into Ofsted will examine:
- What the purposes of inspection should be (relating not only to schools but to all organisations, settings and services under Ofsted's remit)
- The impact of the inspection process on school improvement
- Ofsted's performance
- The consistency and quality of inspection teams in the Ofsted inspection process
- The weight given to different factors within the inspection process
- Whether inspection of all organisations, settings and services to support children's learning and welfare is best conducted by a single inspectorate
- Ofsted's role in providing an accountability mechanism for schools operating with greater autonomy.