No2 rifle cleaning rod guide
These were used to prevent cord wear on the muzzle from the pull-through. Over time the pull through cord can wear a groove in the muzzle.
"Notes for Instructors on the Use of the Rifle October 1918 (General Staff 40 WO 6969). It does specify 'one steady pull ... to avoid cord wear'"
Most have PH (Parker Hale) markings.
Diameter of Muzzle Clamp Pocket in Tool Fully Closed: .550"
Diameter of No2 .22 Training Rifle: .559"
Diameter of P14 Muzzle .598"
Diameter of No4 Muzzle: .592"
This will not clamp to a .598" P14 Muzzle diameter