An academy trust has defended its record in Suffolk and Essex after poor results outside the region saw it labelled the worst performer of all secondary school providers in England.

A report, published today by the Education Policy Institute (EPI), awarded Bright Tribe, which runs Alde Valley in Leiston and Colchester Academy, the lowest score for key stage four (KS4).

The report, which assesses the performance of academies and local authorities, considers factors such as pupil improvement, prior attainment and levels of disadvantage to provide a “clear measure” of performance..

While Bright Tribe is identified as the worst performing group at KS4, the report notes it recently relinquished all but one of its schools in the north while keeping those in the south, including Alde Valley and Colchester.

The trust claimed its poor KS4 rating related to The Whitehaven Academy in Cumbria, which had suffered from a “long legacy of underachievement”, prior to its involvement at the school.

“Other schools under Bright Tribe’s control have demonstrated substantial and sustained progress, with both secondaries in East Anglia now being graded ‘good’ by Ofsted and with progress 8 scores above the national average,” the spokesman added.

“At one school, inspectors commented on the words of a parent who stated that, ‘this school is now the school that everyone is talking about and considering moving their children here’.”

Bright Tribe said it would work to ensure improvements continue.

The EPI found little difference in performance between academy chains and local authorities, and noted cases of “sustained under performance” in both.

EPI chairman David Laws said neither model was key to better schools. “Instead, the government needs to consider how it can act more swiftly and effectively to tackle the worst performing school groups, whether these are academy chains or local authorities,” he added.

Jack Abbott, Labour’s education spokesman at Suffolk County Council, said the findings showed the rush towards academisation was not the answer. “In recent years there’s not been enough accountability over when schools become academies and what happens afterwards,” he added.

Bright Tribe’s KS4 rating does not relate to primary schools, which include Castle Hill and Cliff Lane in Ipswich.