I have to go with 2-tone. And I notice that RG, a fellow British transplant, has voted that way too. I would agree that it does depend on the colour. Plain black, red, or any other primary colour will look wonderful on its own, but either colour works well with others as part of a bi-colour scheme. If you are thinking of having yours painted with an accent colour, then that would be the way to go.....some colours might look a little "too much of a good thing" depending on the beholder, and yours is one of them. An Old English White would be a nice complement to the existing colour. Just my tuppence worth.