John, try these out. They're 5 1/2" diameter lamps, same as the Lucas ones. They're Cibie, so I 'm sure you can find an distributor over there.
They are the "Tango, Series 40" lamps, scroll about 3/4 down the page. You can also purchase the entire wiring loom with relays here as well:
http://www.danielsternlighting.com/products/products.html
I installed them on a Triumph GT6, I think they look identical to the original Lucas lamps used back in the '60s.
Good luck, let us know what you do.