Vintage stamp collection in a leather binder

I lost my vintage stamp collection yesterday around 3pm near the Barbican area in Plymouth, Devon, near The Box and the Mayflower Steps. It's kept in a black leather binder with a red ribbon bookmark and a tiny gold initials stamp on the cover. Inside are clear plastic sheets holding UK Commonwealth stamps from the 1950s and 60s, including a bright blue air-mail stamp and a few mint-condition pennies. The binder has a scuffed edge and a faded inside-cover label that reads 'GB Classics'. This collection means a lot to me—it was a gift from my grandfather, and I really hope to get it back.