On its top there are some remains of an Iron Age's hill fort.

The most phonetically plausible is derivation from Gaelic *cochull-ruadh meaning "red cap, hood or mantle".

[6] Less convincing Gaelic derivations are *cachaileth ruadh, "red gate",[6] *cuchailte ruadh, "red residence, seat".

[6] The name may be Brittonic and derived from *cloc-erjo- (from *clog, "rock, crag, steep cliff", Welsh clegyr),[6] suffixed with rūδ, "red" (Welsh rhudd),[6] but this requires double metathesis and unexplained reversion of -e- to –o-.

[6] Media related to Cockleroy Hill at Wikimedia Commons