622 has long been the 'standard' size for all tubular tires. It therefore was the default size for all framebuilders of 'racing' bikes where tubulars would be chosen. All of continental Europe used this as the 'racing' standard. For city bikes, there were both larger and smaller sizes used.
The 27" (630) size was mainly a British standard, and therefore by default, in many other countries where the British bike industry held sway. I believe it was the arrival of the high quality clincher tires and rims that brought about the decline of the 630 size as more and more 'racers' decided to go with clinchers on their high-end frames built around the tubular standard.
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Steven Maasland
Moorestown, NJ