In Hubert Parry's (1848-1918) choral work "There is an Old Belief", there is a marking in a few places that just reads "Tempo". The first time it happens after a ritard, following a fermata. At the same time as the "Tempo" marking, there is a time signature change from 3/2 to 2/2. This marking is repeated later in the piece after a ritard, but with a lowercase t "tempo".
The reason I'm asking this question is because I have heard different recordings of this piece (and seen different editors' opinions) where one of two things happen: at the time change, the director changes from a quarter note beat to a half note beat (quarter=70bpm changing to half=70bpm), effectively doubling the tempo. Alternatively, the tempo goes back to its original state.
I haven't ever encountered a marking in a score that just read "Tempo"--it's usually "a tempo" or "Tempo I" or "Tempo Primo", etc.
Thanks!