There really isn't a lot of slack in the welfare system unless you're prepared to be very short sighted and go back to "tent city" levels of homelessness. Which is partly why all previous attempts to cut it have failed. Maybe declaring certain areas of high rent off-limits for housing benefit, but then you have to raise the salaries of NHS staff and teachers living in London so they can afford to work there.

Maybe if the Miliband reforms pay off and certain critical things get built and gas prices return to normal, Labour will be able to take credit for lower electricity prices? Unless it's all spent on datacenters, which would be even worse political doom.

Personally I'd go with the "mansion tax" but that requires ignoring the well-connected screaming. They did manage that with VAT on private school fees.

Massive handouts via welfare programs is the only thing that keeps left leaning parties in power anywhere in the west. They've failed at bringing prosperity so they just court retirees, the unemployed and hire more government workers. And unfortunately those who rely on welfare outnumber those who work and pay taxes in a lot of western countries, because of the lack of prosperity... Need to hit rock bottom à la Argentina for people to wake up.