Driving Band is common on all artillery projectiles as the whole round in contact with rifling would heat the round up too much. Driving bands are used as indirect fire weapons are slow twist. The fuse is time limited so it is intended for indirect fire. 84mm base means the driving band is likely 88mm which is the bore of a 25 pounder. Although I am a retired artillery officer, I have no personal experience with 25#QF.
https://en.wikipedia.org/wiki/Ordnance_QF_25-pounder
Someone just said 18 pounder, I had not considered that, I would go with 18 pounder as the shell is not boat tailed. Likely post WW1 training round.
https://en.wikipedia.org/wiki/Ordnance_QF_18-pounder