I've found a 1955 Holdsworth catalogue: https://threespeedhub.com/wp-content...es-1955-UK.pdf
That does show prices for chrome plating, but doesn't mention cromovelato although that could be "mirror flamboyant on polished base".

It also says 'first class Continental "Stronglight" fittings'.
While searching my stash I did find the original headset for my 61 Cyclone which is a Stronglight.
I may well have to clean it up and try to identify it.