Thankyou all very much for your contributions.
The answers I was looking for seem to have beem answered, any more comments are also welcome.
Juswonnafly, the response you gave seems to be the same method I was taught and also that referred to by Yogi, which is the 'quick' [mental] method I was shown for en-route nav and holds etc.
Once more many thanks for those replies and it is good to see that for once a thread has not degenerated into bickering, just useful and constructive comments!!
Now all I need is all these TS to clear and I can get on with flying...
Socrates