Prior to departing I had a quick look at out giant Cardoon, Cynara cardunculus, plant. Its magnificent thistle-like flowers attract hordes of insects in the summer but occasionally insects are to be found on the leaves.
Today it was a Tortoise Beetle, i.e. a species of Cassida. In the U.K. here are twelve species found and a little care must be taken with identification. This specimen turned out to be Cassida vibex, widespread in southern Britain but less common further north.
The beetle, Cassida vibex. Stefen Hill, Daventry.