Why should England provide airbases and army bases for US forces (where US law over-rides UK law) at minimal to no cost?
Favors work both ways. We’d not be giving you the subs or missiles, just borrowing a couple of slips and some accommodations until we can upgrade a port (probably Barrow, it already handles subs) to cope with the Trident systems.
The favor is/has been US defense of Europe so that you can have a socialist nanny state.
There’s no reason England couldn’t lease the current facilities from Scotland, except English spite.