OK, I'm back again.
My mysterious rattle seemed to be getting just a little more regular, and just a little louder, as I drove around to various friends and workmates for their opinions.
I was initially going with the leaking or cavitating oil pump, but was then suggested that it may be the timing belt tensioner.
A garage mechanic (
with SUBI experience) thought it might be the harmonic balancer coming loose.
After each
deduced conclusion, I would hunt through the
Technical Q & A pages dealing with that particular problem.
This morning I took the car back to that garage with an idea of getting them to dig into the problem for me, (
last time I fixed it myself, it took 2 months!) When the young mechainc got me to start it up, my slightly annoying rattle suddenly sounded like a bag of 3 inch nails being dumped into a steel trash can!!
it now has aquired a new
BUZZ to add to the odd rattle.
"
Sounds like your timing belt's f¥@?#d!" he says, to which I think,
'I should be able to do that', so I carefully drive back home with thoughts of those last threads of rubber flailing around up front, just keeping the engine going!
Now after jacking the car, draining the radiator and
removing the radiator, I started to remove the timing belt covers, and a handfull of ball bearings fell out!!
I've yet to get the main pulley off to be able to remove the center cover, but I've managed to rotate the crankshaft and jump a few teeth,
will have to do a total set up.
The belt itself looks to be in good condition?
It may have been replaced just before I bought the car,
although I have no log books 
Got too cold to work, so will continue tomorrow.
Arthur.