Quick update for those interested / who advised me.
Boiler maintenance chappie arrived today, we opened the tank valve again for him to attempt to see where the leak was coming from on the burner. Amazing what a clear view of a problem does to the cure
I had moved the aforementioned freezer, tumble drier, 60's vintage radio system which stood on top of the drier and a number of old cricket bats in various stages of decay from the surrounding area of the boiler.
Within seconds the oil reappeaerd even without the boiler being turned on!
Where did it come from I hear you all ask??
Well it was a leaking something on the damper
5 minutes later, boiler was up and running and I had HEAT in the house again. Calor Gas is definitely not good for the lungs for such a long period.
Next problem

just got to sort out why the programmer is running arse about face. Turn heating on and water comes on, and vice versa. Turn programmer to OFF - and it comes on.
He's coming back on Monday to do a full service on the boiler and to sort out the programmer, it seems that it has been wired incorrectly as the sunvic drawing shows that a terminal should not have any wires connected yet there is a wire there.
Many thanks to all those who offered advice over the past fortnight or so.
As I live in such a crappy house, in the words of Arnie - I'll be back
