Ahh the Bulldog!
It was 1973 and I'm pretty sure that we were the first course on it, after they had replaced the Chipmunks at Church Fenton.
Panic in the tower when a fellow newbie who is halfway round his first solo navex (a wonderful guy with a broad west country accent) calls to say "I think I've got mud on my windscreen"
ATCOs all freeze and look at each other, trying desperately to find the right response to that until...
"I don't suppose that could be oil could it?"
"Oh yes, could be"
Sigh of relief in the tower "return to base"
Happy days.