The 93 FSM shows (printed 8/92) shows the two piece cam sprockets having a spring retaining ring that snaps into a groove in the ID of the toothed cam sprocket (item 12 on the timing chain diagram).

JaguarLandRoverClassic 87-94 4.0 does NOT show a retaining ring.

My rig, which has had the head off before me, has the grooved sprockets but no retaining rings.

Seems odd the FSM would have carried over an outdated diagram.
Also seems odd the sprocket wouldn't move around without the retaining ring.

What have ya'll seen on yours?

 

My 94 does not have the groove. The sprocket ring is held in place on the splines by a plate under the 4 bolts. There is a flange on the rear side of the splines on the camshaft too. I only know this because of my "big head gasket episode of '18"

 

Upon closer examination, The wear pattern confirms Jerry's explanation. The sprocket is captured by the camshaft flange, no clip needed. Finally, something turns out easier than expected.