An education trust which runs schools across the north of England is failing to improve standards, the education watchdog has said.
The Northern Education Trust took on "too many poorly performing schools" and had "unrealistic and unachievable" plans for improvement, Ofsted found.
The trust runs academies on Tyneside, Wearside, Teesside, Northumberland, Yorkshire and Greater Manchester.
The report does not reflect changes made since the inspections, it said.
In a statement the trust said it had "made significant new appointments, injected substantial resources and made major changes to our systems over the last six months".
Ofsted inspectors, who visited nine of the trust's schools in November and December, found standards "below average at every key stage".
Half had improved at their latest inspection but the others had either remained the same or declined, its report said.
'A little shocked'
Trustees and trust leaders had "an erroneous and over-optimistic view of the schools' performance", it added.
However, the trust had a "strong track record of good financial management" and relationships with academy leaders were "constructive and positive", inspectors found.
Inspectors also said trust leaders had been "honest in their evaluation of past performance and their shortcomings in moving too slowly".
"This has led to a planned restructure to ensure that the school improvement strategy is on a firmer footing for the future."
Trust chief executive Ian Kershaw said he was "disappointed, and a little shocked, by the delay" in the report's publication.
The trust had "put in place measures to address the issues and recommendations raised.... some time ago", he said.
The schools it had taken on had displayed "signs of endemic failure" and had "rarely succeeded for decades", he explained.
"Sustainable improvement can often take longer to achieve than government guidelines suggest, or we would all wish."