My thing with England is how did such a small country support such a large empire? (Thinking as it relates to Civ mechanics here) Obviously it eventually broke apart, but it did maintain itself for a while.
Same thing could be asked about Mongols. How did a small group of people (maybe 100 or 200,000 at the time of Genghis Khan) were able to conquer gigantic nations (China) & then takeover rest of the world? Same could be asked about Arabs during rise of Islam.
Thing is that these empires shouldn't be considered tall once they conquered large swaths of land & expanded like crazy. Everybody started tiny. Romans didn't have half of Europe in their pocket when it was founded.
A good tall empire example could be Aztecs, they had a handful of cities & the rest were their vassals. They regularly waged war for captives, not land.
Historically in most cases a tall empire would love to go wide if they ever got a chance.