For my PhD research, I have collected data to create a time series with the size of the British Empire. To obtain the list of conquests, I have used the list produced by Julian Go of Boston University. With this list, I consulted atlases of the British Empire and matched the area as much as possible with current provinces, territories, cities, states, countries, islands etc. You will understand that this is an approximation since even “renowned sources” have slightly different borders for each time period of the Empire (especially with regards to settlement colonization is Australia and Canada). As soon as I have finalized some methodological choices, I will post the entire details in the dataset section so that it may be accessible.