If you are interested in a totally cool third brake light, check out the Grimes model B aircraft wing light on Univair Aircraft Supply's website. I dug around my old parts box and came up with one, red lens. I will be installing it on a machined aluminum (or aluminium, depending of your location) mount, and using an LED bulb in place of the incandescent one.
I believe it fits the Morgan quite rightly.
Best,
tom
Those sure are expensive and that flimsy bale might go adrift and another expensive part fall to the ground and break. The general looks is nice.