US Amazon Prime member available in UK on UK Amazon?

I just tried to sign in with my Amazon credentials from USA. It recognized me but not as prime like a home. You can still use Amazon without prime. Or it looks like I could sign up for free Amazon UK prime trial, maybe use that.

As far as I know only Prime video streaming works overseas. Here is how to switch countries according to Amazon: https://www.amazon.com/gp/help/customer/display.html?nodeId=G3VN2A3K3WBAE2US

No, it isn't.

When we were in London for 3 weeks (in 2016) in an apartment, I was able to order items and have them delivered for free with my Prime membership. But it sounds like things may have changed since then. Still, I would go ahead and start an order, and see what the delivery charge is.

Edit: I just did a pretend order for an item to be delivered to a London address. The delivery charge came to £4.99.

facing the opposite way - as a UK Prime member when I wanted delivery in the US I had to buy a US Prime account. And when I had no more use for the US account I forgot to cancel it, and paid several months I didn't want. They credited back the last 3 months but no more.

As I am someone with Amazon Prime in the U.S., and orders things from Amazon UK while in the UK, I can tell you that your membership does not transfer.

However.........more than likely, the first time you order from amazon.co.uk, you will be offered a free one month trial membership in Amazon Prime. I took it, got all the benefits of Amazon Prime, than cancelled a couple of days before they charged my card for it. Surprisingly, they offered it to me again a few months later.

The last time was this past August.

Amazon Prime US and Amazon Prime UK are two separate things and cancelling one has no effect on the other.