@sophocles,
1728...?
well from a analytic point of view with patterns
London: 4 c, 2 v = 9^3 (512)
Card: 5 c, 2 v = 10^3 (1000)
Edin 6 c, 3 v = 11^3 (1331)
Bir 7 c, 3 v = 12^3? (1728)
my analysis has nothing to do with consonant and vowels, but a mere pattern recognition lol. gl