Was on the 7th hole at my local club approaching the tee with a nice chip over the water trap onto the green for GIR. Slightly over hit the ball which ran off the green by about 6ft, when from behind some trees out pops a greensman on his mower and runs over my ball depositing it a hundred yards or so back up the fairway!

What should i have done (considering I could not catch the blighter on his mower)? Taken a 2 shot drop or play from the balls new position?

I would say replace the ball as near as possible to where it was before it got run over, without penalty. THat is my view.

On the other hand there will be some who say that the ball was moved by an outside agency and should be played from where it lay after the mower had moved it 200 yards.

If in a competition the best thing would be to play both scenarios and then submit the details to the competition secretary for his judgement. 

'Outside agencies' can sometimes be cruel, and at other times amusing.

Last week, whilst practising on the practice ground, I left my pencil back on the edge of the ground whilst I walked 100 yards to pick up my balls. Out of the corner of my eye saw a person's trailing leg entering the bushes next to my bag but thought little of it.

When I got back to my bag my brand new expensive 'Cobra' umbrella, complete with its sheath, had gone. I can only assume that the thief did not take everything as he wanted it to be a 'hidden theft,' possibly interpreted as a lost item. But who knows how a criminal's mind works? Possibly he simply expected rain?

Yesterday I hit 80 plus balls onto a practice green. On the adjoining golf course a player hit his ball out of bounds onto the practice field and his ball ended up with mine. I watched him examine around 20 of my balls then shrug his shoulders and walk away.  

It's sometimes difficult to have fun without experiencing 'outside agency' intervention. 

when a ball has "come to rest" if it is moved by any interference including being hit by another ball. It should be replaced and played without penalty.

same thing happened to me in a society comp at horsforth. lawnmower ran over my ball which flew up in the air and was never seen again. I was told by an "expert" to take a free drop where I last saw the ball... I looked it up later and found he was almost right. But the ball should be replaced not dropped.