Thank you to all of those who sent rep[lies to my dilemmas.
I have, today, called M L and S and spoken to Gary (G0MIT) who set me right on several things. As G4EML has said the CPS has to be updated to the latest version. The set was programmed using cps Version 7.06 and therefore I needed to be upgraded to cps V7.06.
In actual fact I'd gone a few stages further and gone to cps V8.00, but this is too far ahead and although it may be the latest version is not currently intended for use in the UK market.
So problem solved, remove cps V8.00, load up V7.06 (which I found on GB7DD's website), upgrade my code plug using V7.06 and then programme the set. What could be simpler. Having spent the whole day on Sunday converting and re-converting the code plug, reading the radio and trying to import channels etc, etc. I should have done my homework first.
As far as the conversion of the code plug into the MD785, Gary is going to do a conversion job for me. As G4EML says, it takes a hex editor to modify the code and then it an be introduced to another set. Simples. I'll let you know on the other thread how that goes.