Well... sequence of events:-
Development is on pc the application copied to laptop
Updated my version of Lazarus
Compiled an existing application
Main Form back ground colour grey - should be white, checked in the object inspector- correctly defined as clWhite.
Made simple test showing just a main form - correctly displayed as white.
Recompiled my application and it correctly displayed as white
copied the application exe to my laptop displayed as grey.
Made a new simple application with a label and button and it displayed correctly as white
recompiled my original application
copied to laptop correctly displayed as white.
So I have a succesfull outcome but no idea how!