Well, after a day mostly spent moping around and feeling pretty pissed off, I decided that I could either continue sulking, or get the car sorted out. In my experience I’m pretty crap at the former for any proper length of time, so chose the latter 
I ordered a replacement head gasket set from the Gaskets for Classics chappie on eBay – knew it rang a bell when Dave recommended them the other day … turns out I’d ordered the exhaust gaskets for when I fitted the “new” manifold a while back 
Around that point I must have blacked out, cos’ the next thing I knew, I’d left work and the car was magically steering itself towards Machine Mart 
Thankfully, their stuff comes in convenient “car-sized” boxes with “some assembly required”, as the Impreza’s rubbish as a load lugger …
Only took a little while to assemble it, and I got to use some of the sockets and spanners from the big end of the toolbox too 
I then got a really bright lamp plugged in and had a good look around the engine to see just how bad things were before taking it all apart again. The leak at the back appeared to actually just be old oil/petrol that had gone gooey and glazed over – and at the time had looked like water. Shows I should have taken the the time to really clean/degrease the block whist the head was out of the way. 
Of more concern though, was the very slow drip of coolant at the front. It was dripping off the bottom of the crank pulley, but I couldn’t see anywhere above there on the engine with a corresponding dribble running down 
The one thing it might have been was a pool that had formed somewhere before I realised I’d forgotten to refit the temp sender before filling the coolant (remind me not to do stuff when knackered), and it was just coincidental. Either way, it had dripped about a good double Gin’s worth of coolant into the bowl overnight 
After a contemplative cuppa, I reasoned that if there actually were any leaks, they’d become readily apparent once I got the engine going. Worst case scenario is that I’d definitely have to take the head off again if there actually was a problem – but I now had a hoist to help on that score, plus I now knew how it all fitted together, so it would be a much simpler operation this time round. Rather enjoyed that cuppa, I did 
After a few false starts, the engine spluttered into life but was lumpy as hell. I made a guess at re-positioning the distributor (as it’s harder to tell just by sight with the points-less Aldon Ignitor installed) and after a couple of goes it was at least idling. The really bright lamp came out again and there were no initial signs of fatal explosions or impending doom, so I topped up the radiator and decided to carry on and see if it would run for 15 minutes – to satisfy both idle curiosity and the Haynes procedure in equal measures.
Here it is in (slightly lumpy) motion …
Well, after about six minutes of running, the thermostat finally opened, so I knew I was getting coolant flow if nothing else, so I popped the rad cap on and let it carry on. Aside from getting a really dry throat from the poor ventilation in the garage, there was nothing else to report from the initial run. I’m letting it all cool down, then I’ll give it a thorough once over and if there’s no sign of problems, I’ll re-torque the head bolts and give it another extended run. No banana dancing smilies yet though … I’ll save them until I know for sure 
Watch this space then … it could just be that the magic Turbosport pixies visited the car overnight and fixed it with a sprinkling of pixie dust …
Whilst I think on, can anyone take a guess as to what the following small bolt would have been securing on the nearside rear of the engine. It’s only an inch long. I took it off somewhere when disconnecting the throttle, removing the carb and inlet (and carefully put it on the back of the inner wing so I wouldn’t lose it) … but ain’t sure exactly where from now and can’t see a hole that looks like it’s missing a bolt
EDIT 25/09/07 :
Dave : Sounds like all is well, and unless the clouds of steam are so big you can no longer see where you are going, it will be fine. Trust me, I know. 
And there is loads of free water in North Wales anyway. See you at the weekend.
me : Would a water gasket failure be that blindingly obvious within say twenty minutes? Never had one really “go” on me, so I’m never sure how severe an event I’m meant to be looking out for.
lee 1 : You gotta love when a problem fixes itself
If you have run it up untill it’s up to temp and no sign’s of leaks you should be fine.
Sorry but had to laugh about filling the coolant with no sender,i rebiult a fireblade engine a few weeks back filled it with coolant and thought why are m feet getting wet. Turned out i had left the drain screw out of the crankcase
Dan : havent a clue what that bolt is looks a bit like the one on a clamping bracket thats on my exhaust manifold , but if something gets loose or falls off it’ll all make sense