Confidence: I'm as sure as I can be.
Notes: When identifying anything, always read the description. In this case, the description surely stated that C. cristatella is an American species, not known in Britain or elsewhere in Europe. The common name refers to the colour, as in British soldiers' tunics, back in the days when wars were more sporting and soldiers presented themselves as easy targets. There are at least three Cladonia species here, but the ID refers to the main species, with granular podetia, red apothecia and not forming cups. In the foreground are the brownish, non-sorediate cups of C. cervicornis, and also young podetia of a sorediate, cup-forming species, most likely C. polydactyla.