Yes, The Mumbles is definitely a goth band because most of their albums belong to the Second Wave of Gothic Rock genre, which is a core subgenre of goth music. Albums like The Dust Left Behind, The Wire EP, and The Machine [Anniversary Single] are examples of their goth sound.
The Mumbles is located in United Kingdom, England, London, active in 2005 — present. You can find more information about The Mumbles on their GothDB band page.
Want to check if another band is goth? Search other bands.