An article from „Classic and Sportscar“ August 1989 by Doug Nye seems to solve the mystery of the real “gold” color of the JPS Lotus cars from 1972 to 1986 as Peter Warr, then director and general manager of Team Lotus explained it there. I found this valuable piece of information as part of the thoughtfully prepared instructions coming with the F1 Specialties conversion decal sheet for the Lotus 98.
Here is an excerpt of the article with the relevant information.
So MFH got it completely right with the bright yellow decals for the 1974 Lotus 76 kit. And they are correct with the biscuit colored decals for the 1976 Lotus 77. Very good, as this were my recent two builds incidentally.On the 1972-73 John Player Special Lotus 72s the JPS insignia and gold coachlines were applied to a signwritten line of sticky varnish and were sealed over with another coat of varnish on top. In those days a book of gold leaf cost 5 Pounds and around 22 to 24 books were required to signwrite each car!
The number circles on the nose and radiator pods were sprayed, because of the large area involved, “but needless to say this resulted in a difference in color which we were not happy with.” The ad men also found that the cars suffered badly from reflections from the sun in photographs, so in 1974 – when Duckhams began to co-sponsor the team – the cars were signwritten with yellow paint.
Only with the Lotus 77 did Team Lotus adopt Keeps Signwriters Gold which is the flat beige I recall. This finally succeeded in achieving the photographic requirement of non-reflection plus a gold appearance, and of course “considerably reduced the cost of signwriting the cars”. Peter confirms that they maintained this scheme until the end of 1986, and the final withdrawal of the jet black cars from the circuits.
So for my 1974 Lotus 72E conversion I will have to look for yellow decals to compliment my leftover decals from the MFH Lotus 76 decals.