Music needed..

[Scott Pope]

Ken, traditionally, the lowest note of a 3-valve BBb tuba, the instrument that Holst was familiar with, is E natural four ledger lines and a space below the bass clef. Of course, this is the actual pitch, not the transposed notation pitch, of a standard open E string of a 4-string double bass.

This is very convenient, as convention is to simply take a tuba part and play everything up an octave from what is written on double bass. Even today, until you get to some grade 5 or 6 pieces written for 4 and 5 valve tubas, 99%+ of all concert band literature has this same range. Even then, it's only the occasional note, playable with a handful of valves, in the same manner as playing the same notes on a C-extension double bass.

I still occasionally have to sight transpose, both ways. In my jazz/dance band, I occasionally get tuba parts that I play up an octave, and in concert band I occasionally get double bass or bass guitar parts that I play down an octave, or occasionally we'll get a piece that just sounds better on one instrument or the other, or even electric bass, and I just make it work.

Since the orchestra part is available, yes, I'd just get it, because it will take awhile, even with Finale or Sibelius, to rewrite the part up an octave. Then you'll always have it.