Are you tired with the time it takes to fill your Morgan with petrol, and having to leave your keys in the standard flap, therefore hanging on the paintwork, plus the unleaded 'idiot' label?
The Aston 2.5" fuel filler is the answer. Not only does it look very Morgan-esque, but the throat of this filler is large enough to allow for 'venting' when filling.
The locking insert is optional (please specify if you want this option below).
It Is relatively easy to fit, if the existing hole has to be made a bit larger in diameter use tin snips and a half round file. Open up the aperture until it fits flush, once you know that this fits, mask up the aperture with masking tape, drop in the fuel filler to mark holes, in which to drill the fixing bolts. Drill the holes; then remove the tape. Fit the filler using bolts and attach fuel filler pipe, then fit the locking insert. Make sure the hinge to the cap is pointing down, when fitting.