Hmm, looks like I misunderstood the figure - https://agileenergy.net/uk-net-zero-transition-to-cost-1-tri...

So > £1 trillion by 2050, not sure if that includes assumptions about cost reductions in renewables by then though so I'd assume compressing the timescale increases the estimate.

Either way it needs doing and it would seem that 2050 is going to be too late.