Bravo Antonio!
These are superb and a wonderful compliment to the only other images we have of Denis' 500's from Shane on page 4.
Just to place the period, are we talking about late 70's early 80's here?
Our thanks to your Dad too!
ps: I've had 'leaky' oil lines on 500's in the past although these were all rectified by adjustments (or even replacement) of the line itself. But .. I've heard they do things a little differently in Scotland! 
pps: Presumably this was the hangar where TRC swapped out the fuel tank for Denis' 206?