Interesting replies all round and thank you all for your inputs. I usually save Pprune info like these and hand them out to students for "required "reading.
I had a prop stop on me during stall recovery practice in a C150. Decided to aim for a ditching in a nearby river estuary due lack of suitable fields. Fortunately I managed to convince the student to lean back in his seat while I stretched across him to reach the primer pump situated near his left knee. Three hasty pumps and the engine started with first twist of the key. Cancelled Mayday and 7700 and flew home. Snagged aircraft in tech log for low idle rpm.
Occasionally one finds a primer pump that binds badly and is difficult to operate.
This particular Cessna had previously had one of those and I had written it up a few days earlier. Fortunately the techs fixed it, because if it had played up on me when the prop stopped, I guess we would have had wet feet.