Easily mistaken for : other Cladonia species with cups:

Easily mis-identified as : Cladonia fimbriata which also has granular rather than scaly podetia (bits on the side) but the projections from the rim seem to sport miniature replicas of itself rather more often than does Cladonia greyii.

Many similarities to : Cladonia pocillum which also has granular rather than scaly podetia (the bits on the side of the stalk))

Slight resemblance to : Cladonia humilis, the stalks, podetia and goblets are similar, but the squamules around the base are not leafy green, but the same very grayish only slightly greenish as the goblet and stalks. Not as green as Cladonia greyii or Cladonia chloropaea. Also to Cladonia pyxidata, but that has flatter cups more like bowls or golf-tees than goblets, and has corticulate granules within the cup.

Superficial resemblance to : Cladonia diversa which also has goblets, but the fruiting body (apothecia) around the rim are scarlet-red not brownish.

As your Author states elsewhere, it should be noted that he does not use lichen spot tests for identification purposes, but relies instead on visual inspection. As far as he can ascertain, the above photos correspond more closely with those of Cladonia greyii (which is usually thrown in the Cladonia chlorophaea agg.) than the similar species mentioned above, but without chemical testing he cannot be certain. Cladonia chlorophaea agg. is also ubiquitous throughout most of the UK, and seeing as your Author did not go out of his way to find this, but rather the lichen attracted his attention by waving to him as he passed, this may add weight to his otherwise rather weak argument. If it looks like a duck and quacks like a duck, then it's a saxophone.