Hello Adrian
I tracked down a problem piece of code / third party component that appears to be causing the issue, I am not sure why.
I run the code at the start of form creation and the flexcel load procedure after.
The component is 'Kryvich's Delphi Localizer'
http://sites.google.com/site/kryvich/localizer
The component is a localiser for language strings, so I am guessing its causing a change to the string.
It is strange that the problem has got worse over time, yet the code for flexcel loading has not changed.
Thanks for you help.