Alfred Hitchcock owned Sealyham Terriers. One of the breeds that I've only heard about; not seen in person.
They were quite popular in the 30's and through to the 50's, - by the 60's there was only a couple of breeders who gave multiple show entries. I have only seen one at the shows lately - but terriers are not always on the same day as hounds. I did see a young pet Sealyham just a month ago - a rare sighting! I had a browse online and one entry says that in 2023 it was estimated that there were fewer than 500 Sealyhams worldwide. There has been a campaign to save our vulnerable native breeds, so maybe there could be an improvement in their popularity.
Just for interest I checked the Sealyham entry at Leeds Champ show today. There were 18 entered. Sadly, six terrier breeds had a lower entry even lower than this.