A large number of older bikes have been imported into the UK over the last 15-20 years from the USA, and not just British bikes but plenty of the larger capacity Japanese '80s/90s bikes as well, because they could be bought very cheaply in the US at that time.
The interest in classic bikes kicked off over here in the UK somewhat earlier than in the USA I think, and some people were going to the USA and buying up these bikes, and sending them back to the UK by the container-load, and either registering and selling them, or a customer could buy cheaper if they did the registration bit themselves.
I'm sure this was a reasonably profitable occupation for a while, and US market bikes are still finding their way into the UK, although as we know, prices have been rising in the USA due to the interest in classic bikes.
Yup, prices are rising. I see a lot of older bikes (70's and 80's) on the road here. They make excellent daily riders, even today.
Many Suzuki models can still be purchased at bargain prices, if you don't have to have one that's show quality. They're great bikes, although not as highly regarded by the collectors. I purchased my T500 and my GS1000 for $800 each. They both needed some work, but are nice original bikes with clean titles.
You don't get much for $800 in the brit bike world these days!