This is Mirabilis.

I noticed these for the very first time one evening in Skiathos. What attracted me at the time was that they appeared to have different coloured blooms on the same plant. I later discovered that there are variegated varieties, on which some flowers can be 100% one or other of the two colours, but most of the blooms on those look like they have been splashed with paint. It's unlike any other variegation I have even seen.
Just found this which goes a very long way to explaining their unusual colouring.
I went on to collect them in every available colour for our cottage garden, and I did the same with morning glories in blue, pink and mauve. I liked the combination because morning glories are open from breakfast time until about mid-day and mirabilis are open from evening until breakfast time.
I saw them again last month in France but I never expected to see them here.
I have also seen Oleander in Bedford and Lantana in London, all flowers I have been missing and completely unaware that they could survive in UK.
It's beginning to look as though I might be able to recreate my Greek cottage garden, at least in part.