minor mm rear axle filler access cover

[tbucketmad]

hi all and merry Xmas , my car (52 mm 2 door sidevalve ) is missing the round metal cover that is under rear seat that allows acces to rear axle filler ,does any body have one for sale as i think that is how mouse got in car and ate my new morris minor owners club beanie hat that i found under seat , i know i could just screw a plate over it but i would like the right bit atb steve
p.s when i say atb that is not directed at the little furry git that has eaten my hat

[tbucketmad]

many thanks carlo for your help