Hi Paul & Lee,
Paul has already outlined what he identified the problem to be - I am confirming his findings/suspicions.
I have now obtained the correct Pi B+ board from RS, jury rigged it all together to test it and voila, it all seems to work OK.
So my message to everybody is simply make sure & thoroughly check that you have been sent the correct Raspberry Pi B+ board when you actually receive it.
As Paul said, it is very difficult to actually read the printing on the top of the board, but it can be seen if you look closely and/or use a magnifying glass.
In addition there are white bars on the headers of the correct board, whereas the ones on the incorrect board are all black in colour.
I would also strongly recommend using the list of known parts as trial and error has now proven that these components will all work together.
Believe me when I say that it is extremely frustrating when you think that you have done everything correctly, only to find out that you have purchased incompatible components.
Thanks again to Paul for making the time to come over and help sort this out - helping each other out is what I think this whole project is about.
Lee if you can eventually get the program to work with the P2 B board, I will readily construct another unit.
I am member of the LAA Redhill Strut and some of the guys there are interested in PilotAware, so now that I have a working unit I can demonstrate it to them and maybe some will go on to construct their own.
Thanks for your own continued hard work in addressing all of the issues that idiots like me keep throwing in your direction.
Regards Alan