This is one where there's no debate. The name of this charming fishing port is 'Foy', not 'Fow-ee'!
Launceston
Our local market town is pronounced in various ways, even by locals. Most Cornish folk will tell you it's 'LAN-sun', not 'LAUNCE-tun' or even 'LAN-stun', but all 3 variations will be recognised.
Chysauster
There's an Iron Age village at Chysauster (near Penzance) which is well worth a look if you're in the area. There's a little confusion over the pronunciation, but most will tell you it's 'chy-ZOY-ster', not 'Chy-saw-ster'.
Trebah
Hands-up, I've been pronouncing this place wrong my entire life. Apparently the name of these beautiful gardens is pronounced 'TREE-ba', not 'Tre-BAR'. Who knew?
Heligan
Another botanical mispronunciation. Although most locals say 'HELL-iggan', technically it's 'Hell-IG-gun'.
Marazion
Overlooking St. Michael's Mount, you would have thought it's popular enough to be pronounced correctly. It's 'Maraz-EYE-un', not 'Ma-RAZ-ion'.
Liskeard
This market town's name is a mystery to many visitors. We can confirm it's 'Liss-KARD', not 'LISS-kard' and certainly not 'LISS-keard'.
Roughtor
The second highest point of Cornwall is a rough tor, strewn with boulders, but don't let that fool you. It's 'ROW-tuh', not 'ROW-tor', or 'RUFF-tor'.
Polzeath
A trendy surf spot that's also a hit for the families. It's 'Pole-ZETH', not 'Pol-ZEETH'.
Widemouth
With Bideford ('Biddy-fud') up the coast, and Wadebridge (Wade-bridge) down, it's not surprising that people get confused. Most locals will insist it's 'WID-muth', not 'WIDDY-muth' and definitely not 'WIDE-mouth'.
BONUS:
Poldark
Not a place-name, and not really even a Cornish name, as it was made up by Winston Graham. However, according to Cornish speech patterns, this should be pronunced 'Pole-DARK', not 'POL-dark'. To be fair, the series do try and make that distinction.