After the Brexit vote, falling yields have led to the aggregate deficit of pensions schemes in the Pension Protection Fund (PPF) rising by more than 18 per cent since the BHS scheme entered the PPF.
This means the estimated sum required to pull the BHS pensions scheme out of the PPF has ballooned from £275m - the original liability estimated by the PPF - to over £326m now.
Deloitte and Linklaters are acting as advisers to Green over how he should help the BHS pension scheme - but negotiations with TPR are expected to be lengthy, and Green has hit back at Frank Field MP, chair of the Work and Pensions committee,who has called for the retail tycoon to simply write a cheque.
In a letter to Field sent last weekend, Green said: "Your repeated attempts to lead the public into thinking that it is simply a matter of me writing a cheque are utterly disingenuous.
"The Pensions Regulator has its own processes that we are obliged to follow...It is no secret that I have found these processes cumbersome and slow, but they are the processes which Parliament requires the Pensions Regulator to follow and the pace is determined by the Pensions Regulator, not by us."
He added that "real progress" has been made towards a solution, but that Field's inflammatory language "puts a solution at risk".
Green has described the MPs' select committee inquiry into BHS as "little more than a kangaroo court".
He has also threatened to sue Field for calling him a thief, prompting Field's lawyers to apologise. City A.M. understands Green is still considering his position over the question of legal action.