Oil line tap
 

Finally I've put all the bits back together,all I need to do now is go and get some fresh petrol.
The only thing thats puzzling me is:- there is a tap switch in the oil line between the crankcase and the cooler from which the carb heater lines branch off.......which direction should it be pointing?
,it can either run in the same direction as the main oil line from the engine or turn 90 degrees and point along the heater line,and what does it isolate in each position?
If this doesn't work after this,I'll swear you'll hear me swearing over the whole country.:D:saint:

That's the carb heater tap, I believe. If it's pointing towards the heater line is on (winter position) otherwise it's off (summer position). Mind, you have to leave in "winter" position all year long in some places.

Thanks Felix.The howling gales and driving sleet here are pointing me towards a winter position I think.;)