Meaning obscure, but it tended to be wheeled out when ships were spoken of
Possibly derives from some parody of the song The Saucy Arethusa (1796) which relates a noted sea fight between the frigates Arethusa (British) and Belle Poule (French) in 1778.
#speculation
Granny Dixon – 1960s
Marion Dixon (Howes) – mother of Mum, spouse of Pop
Granny didn’t apply it to the revered steamer St Tudno, which passed Rhos-on-Sea daily on its way from Liverpool to Llandudno