Davis and Huttenback

In 1986, two American economic historians published the most rigorous quantitative study of British imperial finance ever attempted. Their conclusion was precise, remarkable, and largely ignored: imperial investment produced lower returns than domestic investment. The British middle-class taxpayer subsidized the empire's defense, effectively transferring wealth to a narrow class of investors who held imperial securities. Empire, they found, was not profitable for Britain — it was profitable for a particular Britain.