I am not a great fan of Gordon Brown or most of his then Labour colleagues, but this is what the Telegraph said back in 2010 regarding Prime Ministers' pensions and what GB claims:-
"Regardless of how long he or she serves, any former Prime Minister is entitled to half his £194,250 salary index-linked against inflation for the rest of his life. Mr Brown voluntarily waived his right to this payment – but the entitlement remains in legislation for whoever his successor might be; even if they only hold the post for a few months." (I think there might be some sort of review taking place as to the fairness of this sort of arrangement).
"........ Gordon Brown and Jack Straw have entered into voluntary agreements, which means they have refused to benefit from the arrangement regardless of legislation.
"Mike Warburton of accountants Grant Thornton commented: “Whatever the outcome of the current negotiations to form a coalition government in this hung Parliament, we now have the prospect of a party leader, elected or otherwise, taking residence in number 10 and finding his or her stay is a short one.
“That will not prevent them immediately qualifying for a 50 per cent index-linked government backed pension for life. It makes the cries in the various political parties’ manifestos for ‘fairness’ ring rather hollow as we all prepare ourselves for a period of austerity.”
According to an article in the Daily Mail in 2012, David Cameron has also waived his entitlement to half his salary, index-linked against inflation for the rest of his life.
However, the DM also reported that Tony Blair receives £75,000 per year (which will increase as it is index-linked against inflation) and £115,000 for "public duties" (whatever that means), plus £250,000 per year for "security". In my view, for someone who has an estimated fortune of £30 million, he has got some nerve.