Huh, I didn't know these were a) a 'thing' (as in, more than one across the UK, and b) officially called 'magic roundabouts'.

I've encountered one in Hemel Hempstead; it was a little scary (istr you can see traffic coming 'towards' you), but the article makes me want to go back and try it out again.

Edited to add: Between this and the horrific Welwyn Garden City one-way system, I guess Hertforshire must have (or have had) some of the maddest traffic planners in the UK...