Most Peculiar "Air Raid Helmet"

The below helmet is currently on eBay and it's something I have never seen the likes of before. From the images (check out the link to see more) you can make out "Air Raid Helmet" and "Grimsby" with a patent pending number. Perhaps a company hoping to make a few bob on creating a helmet for civilians before the Zuckerman helmet was released in 1941.

UPDATE: I have been informed that a number of companies made a similar style of helmet. See the advert below for the 'Defiance' helmet. Seems a number of these helmets came into production around the time of the Munich Crisis in 1938.

Most Peculiar "Air Raid Helmet"

Advert for protective helmets.