Why did England annex the colonies in the 19th century?

Britain in the 19th century was called a country over which the sun never sets, so vast were its overseas possessions (Canada, India, Australia, Afghanistan, Egypt, Sudan, Burma, Hong Kong, etc.).

The geographical position of England (a group of islands with scarce natural resources), although it protected it from invasion from Europe, hampered its economic development, the rapid growth of which became possible only after the construction of a powerful fleet and the active seizure of colonies.

The goal of colonialism was to seize new markets for the goods of the metropolis, to attract cheap or gratuitous labor (slaves), the possibility of barbaric exploitation of the natural resources of the controlled territories. At the same time, it became possible to control the most important trade routes, restrain other powers, get rid of unwanted elements in the metropolis (exile of criminals), test new types of weapons and equipment.