Brown Job - let's leave aside the cavalry in which confusingly just about everybody is a corporal of sorts! My point was that although you are correct in that these are the substantive ranks, the terminology in the foot guards does not (or did not) include the term lance corporal, and lance sergeants are/were normally referred to as sergeants. All my father's paperwork which survives (duty rosters, etc) refer to him as "Serjeant (sic) *****", although no doubt on his paybook he was listed as Lance Serjeant *****, and paid as a corporal.
By the way, as a matter of interest, does the appointment of Trained Soldier still exist?