Last three '700' refers.
RPSM11104000 - Technical Pages: Lifetime allowance: Valuing benefits on BCEs: contents
Follow the link through to 'Payment of a relevant lump sum (BCE 6)', then: RPSM11104710 'Lump sums covered (a relevant lump sum)'.
The Lib Dems want to reduce the Lifetime Allowance even further to £1,000,000.. at which point Wing Commanders need to be worried. Without restricting it exclusively to those with suitable seniority, but anyone currently at Group Captain level should be taking a view on this, to the extent of considering negotiating a post mil civilian contract without the superficially attractive pension contributions and something else instead.
Even if the Lifetime Allowance wasn't reduced, it's still easy for the government to revalue a public sector pension, as it did a few years back.