Given that nobody has an investement horizon of 100 years and that the Bank of England has already aquired 25% of public debt using printed money, I think the true purpose of the 100 year gilt is as a vehicle for the Bank of England to effectivelly pay the state debt with printed money. With such a long maturity, principal will not need to be repaid in our lifetimes so this acts as a repayment while being shown "in the books" as debt, so the BoE can claim they sterilized it.This is scary stuff: this kind of la-la land accounting and "financial innovation" were also done in the Weimar Republic.