Hi Kev, The colour on your tank looks about right in the photos you posted. I T-cut the under side of a new old stock tank and mudguards I bought from David Holder, years ago . Turned out to be British Standard Maroon. It matched a few car colours when I cross checked, Volvo 21, and BMC ruby, comes to mind. Matt Holder would not have used anything special!. Some thing which was local, and cheap ,would have sufficed.