Hi. Hoping someone will be able to help with the marks on the base of this Mdina dish. Found in the North West of England, it measures 14 cm x 12 cm x 4.5 cm (L x W x D) and weighs just over 350 gms. Good marks on the base - Mdina, 74 27A, and what looks like OS. I think 27A refers to the shape (a leaf dish) and am guessing that 74 may be the year of manufacture but I have no idea what OS is for. If anyone has any idea or can correct me on the above it would be much appreciated.