Imagine spending fifteen minutes flicking through the rails at TK Maxx in search of a pair of jeans that fit, only to chance upon an Armani suit, in your size and reduced to £7.50. You wouldn’t be half as lucky as the anonymous metal-detectorist who found the Crosby Garrett helmet, one of the most significant archaelogical finds made in this country, and surely the most hauntingly beautiful. Part of a Roman cavalryman’s ceremonial costume, the helmet was discovered in 67 fragments; once fixed and polished up it was valued at £300,000. After a bidding war it sold for £2.3 million.