[contravariant]

The one coherent explanation I can come up with is that they want to fund it by taxing people/companies that evade taxes.

Though that doesn't sound right for the current UK government.

[lmm]

That money would normally go into the tax bucket, so it's really still being taxpayer-funded in that case.

[contravariant]

Well they're not currently taxpayers at the very least, in contrast to the leaseholders who presumably are mostly taxpayers.

[lmm]

Are you being deliberately obtuse? Money is fungible, money recovered from tax evaders rightly belongs in the general taxation pool, funding X with money recovered from tax evaders is no different from funding X with money from the general taxation pool (unless X somehow enables recovering more money from tax evaders that wouldn't otherwise happens).