From the introduction:
The 19th Century was the grand time of Empire. New lands could be annexed by working class soldiers ever eager to find a King’s ransom in loot. The sons of the middle-class could hope for a better life in Colonial service and the younger sons of ancient families could earn themselves a name and perhaps even lands of their own. These quests would take them across the worlds, exploring jungles and wastelands unknown to "civilised Man". Of course the people living in these foreign, "unexplored" lands might rightly be said to have a different view of these adventurers, merchants and empire builders suddenly turning up on their doorsteps.
Nevertheless, before science-fiction the prime adventure genre was the fiction of empire, full of men who patronised the natives as a class but who treasured the friendship of individuals; dissolute Europeans or crafty viziers for villains; lost cities, bandit tribes and the sort of place where a stiff-upper lip and the ability to ride well were damn near all a gentleman needed and, unless a plucky adventuress or a native princess taking pity on an imprisoned chap, women were hardly seen.