Millions of pensioners and homeowners in London and the South East could be in the firing line after a leading left-wing think tank urged Prime Minister Andy Burnham to shift the UK's tax burden away from young workers and onto older people and property instead.

The Institute for Public Policy Research (IPPR) argues the move is essential to cope with the rising costs of Britain's ageing population, warning that by 2075, nearly 80 percent of the extra financial pressure facing the country will come from an older demographic. The report, authored by Oxford professor Ben Ansell, calls for a sweeping new "fiscal contract" between generations.

Among the most eye-catching proposals: extending the 2 percent National Insurance surcharge, currently paid only by workers under 65, to pensioners as well. The think tank also wants to scrap council tax and stamp duty entirely, replacing them with a single proportional property tax, a move that would hit expensive homes concentrated heavily in London and the South East hardest.

The report also proposes equalising capital gains tax with income tax rates, while separately calling for a rethink of how the booming AI industry should be taxed as it reshapes the job market.

The timing couldn't be more pointed. Burnham has already refused to rule out tax hikes in the upcoming Budget, telling reporters this week that he "won't be unrealistic" about the state of the UK's public finances, fueling speculation over just how deep these changes could cut.