There's no govcloud in the UK; unless there are specific terms then the terms-of-service state that you are licensing either the irish entity or the american entity to have access and dominion of your data.
I had to spend a lot of time writing my privacy policy (perks of being CTO... yay), and part of that privacy policy was an admission that we transfer ownership of data to a US company (by using public cloud) despite using european datacenters.
This is because our agreement is with a US entity.
eu-west-2 is a bit misleading, most of its nowhere near London, they've got DC's right up into the midlands. One of their newer ones for example is out in Didcot Oxfordshire, they've also got a few up towards Peterborough. All classed as 'London' despite being a fair distance away from it.
I had to spend a lot of time writing my privacy policy (perks of being CTO... yay), and part of that privacy policy was an admission that we transfer ownership of data to a US company (by using public cloud) despite using european datacenters.
This is because our agreement is with a US entity.