353V: Orphan Cathy Runs Away to Scotland and Learns True Name (Solved!)

I’m looking for a British children’s book, likely from the late 1940s, about an orphan girl who lost her parents in the Blitz. She’s found wandering London with a torn tag that says only “Cat” so the orphanage calls her Cathy. Several years later she has a sudden recollection that makes her feel that her family is in Scotland and runs away to find them. Meets some siblings who help her and have a kind uncle named Alastair. Lo and behold, the kids end up being her cousins, her name isn’t Cathy, it’s Catriona(?) and she is reunited with the family who have been searching for her all these years. Might be the first in a series, a la the Boxcar Children. Thank you!