It's an good colour, isn't it? But I doubt that there is an RAL code for it - Holdsworth having been
swallowed up by Falcon before the use of RAL codes became widespread among bicycle painters.
You can look at RAL shades
here. What you see will be very dependent on your monitor; Deep Orange looks about right on mine.
When I asked for a bike to be painted Holdsworth orange, what I got was a kind of salmon pink - I won't name the company responsible. However,
Argos Cycles did an excellent job of matching the yellow of my Kingcycle. I bet
they could do a proper Holdsworth orange.
PS I expect you've already found
this page? Classy machine, the Super Mistral