Thanks folks ❗
Checked hoses and found signs of leakage when hot from o/s front top hose. Got 3/4 turn on jubilee clip and leakage seems to have stopped.
Warm weather has brought on the dreaded K series click from the starter motor, so have wrapped all 4 ex pipes in cladding in hope of keeping starter motor a bit cooler, pending fitment of starter relay as suggested in LF article a while back.
I'll continue to monitor oil situation, but am tempted to get rid of sump foam altogether as I only use car for touring, no track work. No budget at present for dry sumping. Any pertinent advice appreciated. Thanks to all.