Have you checked that the spinners are tight on your presumed wire wheel. Had the self same squeak recently. Couple of hefty bangs with the supplied lead hammer and problem gone.
If you look on the MWS website (the supplier of wire wheels to Morgan) they suggest a couple of light taps after hand tightening and the direction of wheel travel will tighten it up. Watch old films on Youtube, every one I have ever seen at Le Mans etc there is a big hairy Italian knocking ten bells out of the Ferrari wheel spinners.
I know which one I trust!
