A hacek or háček (pronounced "'hatchek") is a diacritic (also known as a "caron") placed over certain letters to indicate palatalization[?] in the orthography of some Slavonic languages, such as Czech, and the Baltic languages and Estonian. It looks like an inverted circumflex and its name means "little hook" in Czech.
... end of the Metropolitan Line, and stretch the definition of "tube station" a little:
Waddesdon tube station[?]
Quainton Road tube station[?]
Granborough Road tube ...