Murray, you have luck. The wiper Arms (and all associated drive/electrical etc) are Lucas and they are manufactured in the UK ;-)
here is a link to where they sell the Arms.
http://texautomotive.com/classic_wiper_arms.html
I use a 15" on the left and 14" on the right and if you get the Arms that are adjustable in length it is really easy to setup a nice swipe. Since your car is RHD you might need to experiment with different Blades than I use.
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