Sheldon Brown's opinion was that top tube length was the most important characteristic for frame fit. The frame top tube length that suits you depends on both your skeletal proportions (taller vs shorter above the waist for your height) and your preferred riding style (stretched out vs more upright); while the seat tube length is related to your lower extremity length (typically measured as "pubic bone height"), but the range of preferable/acceptable sizes is perhaps greater with seat tube, since seatposts typically have a fairly large range of adjustment, and lengths available.


As philbob57 said, many English bikes seemed to come with 57 cm top tubes, while the French seemed to prefer 59 cm, in my size range anyway (59-62 cm CTT). But lots of makers, especially the custom makers, would fit or suit customer preference.