It's very well known in some areas of Europe, from Wikipedia:
"Keeping Up Appearances was a great success in the UK, and also captured large audiences in the US, Canada, Australia, Denmark, Finland, Sweden, Ireland, Belgium, and the Netherlands. By February 2016, it had been sold nearly 1,000 times to overseas broadcasters, making it BBC Worldwide's most exported television programme."
Dunno if this is known outside the UK