Now on to the next challenge - an Excel formula to work out the track between two sets of coordinates. Any ideas Groundgripper?
Er, no! And sorry for the delay in responding - busy this weekend. As you will have seen, there are greater minds than mine responding to your query.
Stoney X: yes, I realised that it was for a true sphere but had (and still have) no idea about what difference that would make - my interest has never required that accurate an answer! I did google on WGS84 and read
this article in Wikipedia, but halfway through everything went blurred and I had to go and have a lie-down in a darkened room for a time!
GG