The institution’s decision is thought to stem from a desire to orient itself as a more research-focused university.
Northumbria, whose vice-chancellor is Andrew Wathey, was ranked 50th on research power in the REF, up from 80th in the 2008 research assessment exercise.
A Northumbria spokeswoman said the decision to leave the alliance – which was effective from 1 May but was never announced – “reflects the future direction of Northumbria University identified in its strategy”.
She continued: “We see high-quality research as an integral part of the university’s future, driving success across the full range of our activities. This has been, and will continue to be, our position.”
The spokeswoman said that Northumbria had “valued our engagement with the University Alliance and will continue to support arguments made by the alliance where they align to our own position”.
Steve West, University Alliance chair and vice-chancellor of the University of the West of England, said that the group’s institutions aspire to make a difference to their cities and regions. “Our strengths lie in high-quality teaching and research with real-world impact; and we use these, together with our close links with industry and the professions and our global partnerships to transform lives and deliver growth.
“Collectively, we seek to shape higher education and research policy for the benefit of our students and business and civic partners.”
He added: “Members are free to pursue strategies that veer from this mission and, as such, our membership is dynamic. We are comfortable with this.”