While its true that the US may well pay the UK to do things that no longer fit the UK’s role in the world (e.g. maintain bases, with spying setup, in parts of the world from which the UK has withdrawn its imperial control systems), its also true that the US pays the UK to “be the thug” – that it cannot be itself (overtly).
UK – or “rent a thug”.
We see this particularly, over time, in how the spying rationales play out. For example, it was not long ago that scientists were under the crypto-thumb (of NSA); not allowed to touch areas of math or computer science. Perhaps one remembers the “visits from the men in black”; or the sudden revocation of tenure as the university faculty system was “used” to impose hidden science policy. Today, we see the battle being played out on the next field: indirect control and self-censorship of the (UK) press.
It appears that the fleet-street “old-boy” network of control over the press has broken down – with the internet-era newspaper no longer affording the luxury of time windows (in which to get stories withdrawn, etc). We see now the last vestiges, in MI5, GCHQ, etc, of the ASSUMED control practice over the press being played out – hoping that somehow the old control systems can be renovated – now for the internet era.
What we now assume is that there is a conspiratorial element within the highest levels NSA that is acting to subvert US public policy – by having the UK act as their proxy, playing out the thuggish role in the debating forum in a strong “hint” to what MIGHT happen to the US parties, if they fall out of line.