I think a persuasive argument can be made that British financial capital, at least, was not seriously constrained by those capital controls.

In Ricardo's time there was no need. The opportunities were right there in Britain. Plus, until 1815 there was the minor annoyance of the Napoleonic Wars. This probably remained the case at least through mid century. Why send your money overseas if there are ample opportunities at home, where you can keep a close eye on it and influence the government through known and traditional means?

By 1880 there was a need by those who held the capital, and who had great influence over the government, to find profitable investment opportunities abroad lest they cause the price of labor in Britain to rise and the return on their existing investments to decline. So long as they could manipulate the government into providing basic security in a destination country, such as India or South Africa, on pretext of colonial rivalry or "national interest" they could manufacture rails and locomotives in the U.K. from existing plants, build and operate railroads, etc. in India and South Africa, thereby bringing vast hinterlands into the reach, through their control, of "the market."

As the Dutch said while fighting the Spanish: "It is not necessary to have hope in order to persevere."