Also, after driving to track days in my helmet, I decided I needed an inexpensive one for use around town, and general street driving. It'd be really annoying to get a rock chip or a broken visor on my racing helmet on the way to an event. So monday I picked up a Box BX-1 motorbike helmet in red.
After a bit of a drive with it yesterday, I'm very happy with it. It's quiet and comfortable, and the field of view is fantastic for street use. If anyone drives their Caterham around a lot, and is tired of wind destroying their eyesight and hearing, buy one of these, it was £60 and comes in a number of colours (even pink).