The definitive guide to British Mosses and Liverworts is by E V Watson and I have had my copy sines the 1980's; it is essential bed time reading for insomniacs! It is a text book containing incredible detail on what must be a thousand moss species and is a quite remarkable book on a subject that not too many books get written about.
Mr Watson says that this species, the redshank moss (Ceratodon purpureus), is one of the two most common species of moss in the British Isles, the other being hypnum cupressiforme. Is is, however, a very variable moss and can easily confuse the beginner ... all mosses confuse the beginner in my opinion. All is not lost for us mortals starting out looking at mosses though as this particular species likes bare ground, especially burnt ground on heaths. We have lots of heath in south eastern Dorset and bare patches where conservation work has involved burning heaps of cut gorse or rhododendron means that you can encounter suitable habitat with this moss on it quite frequently. It is widespread and also grows on walls and pavements and is one of the most common mosses found in towns and cities being totally unaffected by pollution.
As its scientific name purpureus implies this plant has a reddish or even purple colouring to it.Ceratodon purpureus: the fire moss