Hi
My car is royal ivory (maybe the same as yours) in which case the paint is manufactured by ICI - well at least on my 1997 4/4 it is. I had to go to a specialist paint supplier that supplies the motor trade.
The down side is that I had to get a half litre and buy a fine brush 'cos they do not do those natty touch-up paint bottles.
Hope this helps.
Martyn