St Mary's (EN) / Pluw Varia yn Syllan (KW)

Parish: 
Hundred: 
Elements: 

Maria

This refers to the name of a person: 
name

pluw

Meaning: 
parish

Syllan

Meaning: 
Scilly

-yn

Meaning: 
little (diminutive suffix)
Elements notes: 
<pluw> 'parish' + <Maria> personal name + <yn> 'in' + <Syllan> 'Scilly'