Welwyn and Letchworth
"It further noted that "Welwyn Garden City and Letchworth Garden City also styled themselves as cities despite not holding city status from the Crown""
Unlikely. They style themselves as "Garden Cities" (which is kinda like a snobby version of "New Town"), true, but their councils are "town councils" not "city councils". They only mention the word city because it happens to be part of their official name.
You might as well claim that electrical retailer Circuit City styles itself as a city...