Another entry for this topic...
The January Newsletter for the BMC/Leyland Heritage Group reports they have a complete set of BMC Materials Specifications Standards for all kinds of metals,paints, plastics,seals, etc. The article mentions Standard L66 as the "complete official specifications for Hydrolastic Fluid". It goes on mention the various colours/components as Winabbey reproduced in an earlier thread, then concluded "The supplier listed was Anglo Design of Brookvale (which now operates as Anglomoil in Hornsby and still sells fluid - the fluorescent green spec- in bulk quantities)".

Bill