Yes, English had crazy fertility rate. At the begining of the Hundred Years’ War France had population of 17 million and Britain(excluding Ireland) had 4 million. By the time of Napoleonic wars Britain(with Ireland) had 17 million people compared with 30 million in France. English also had much higher emigration rate to colonies.
When the First World War started UK had a larger population than France.
When the First World War started UK had a larger population than France.