Last month it paid in an extra 85 million into the scheme as part of the so-called recovery plan to address this deficit.

Some countries faced years of consolidation to address their deficit.

The trust, which has launched a 90-day consultation process, said that it needed to save money to address the deficit, which emerged only this year.

It agreed to pay a big one-off contribution help address the deficit, and to pay an extra 50m a year as long as it had 1.8 billion of net cash.

It had chosen a defined-contribution scheme because this would address the deficit without increasing costs to members or diverting money from teaching or research.