Thanx guys.
I guess the VCH mudguards should be unpolished alloy.
I see Hitchcocks motorcycles have 4" front and 5" rear European made, universal unpolished alloy mudgards in stock.
I also have a Seeley Matchless G50 replica classic racing bike and am familiar with the corrosion on magnesium parts ...

I have had a 1951 VCH engine fitted to my 1937 Ariel VB outfit since 1994.
I have now put the original sidevalve engine back in the outfit and will start the process of building a VCH replica.
The only parts i have from the original VCH is the engine and gearbox.
A local jack of all trades acquired ...