I was on the following week's Mountbatten course. The staff were, understandably, jumpy.
We still did the drills in overalls, but the staff DID check that we all had the correct certificates to show we had been checked by the medics at home base. Those who did not have medical chits were sent home.
I believe that MP Howarth did have the correct documentation.
Mt later courses (1969 to 1995)were done with Immersion Suits.