I think rather that only the later (531C) style decals were *commonly* available when owners realized that the originals were wasting away, and placing them on the down tube makes it more visible (not hidden by a pump for example). There's nothing "Holdsworth" about either that decal or the placement, many French bikes place the decal on the DT, too.
FWIW, I doubt that that Holdsworth is in fact full 531 given the stamped dropouts: it could be 3-main-tubes DB or all straight-gauge, but I'd caution "buyer beware" (until somebody corrects me).
Edit: just looked it up on Norman Kilgariff's site: "The Equipe was launched 1969-71. It has plain gauge Reynolds tubing" also came with Valentino gears, not a Team replica despite the colors, just a wannabe.
And besides, NObody would mistake that ornate lugwork for a typical Holdsworth, I think they just liked the color combo, and so do I.
Last edited by unworthy1; 05-18-08 at 09:35 AM.