None of which maintained an array of cannons pointed at the incoming ships attempting to trade at any Primary port.
If you have an example of British maintaining forts overlooking the entrance to Boston's, New York's, or Philadelphia's harbors, then I will concede you have a point.
First, regardless of your current fantasies, in 1860 Charleston was far from a "primary port".
Today Charleston ranks as the #34 US port on this list, while in 1860 it was 22nd on this list -- behind even such Southern cities as Baltimore, New Orleans, St. Louis and Louisville, KY (river ports).
Also, remember that in 1860 major Southern port cities were interconnected on a network of railroads, such that goods & passengers arriving in any one port could quickly transport to any other.
Third, Fort Sumter, as manned in 1861, was useless for any serious military purpose.
It served only to protect Union troops sheltering there.
By contrast, British forts on US lands after the Revolutionary War controlled important trade and travel routes among the Great Lakes.
This at a time when water transport was the key method for moving goods from point A to point B.
Further, Brits had specifically promised, in the Treaty of Paris, to abandon those forts, then refused to do so, for over 14 years!
By more contrast: no promise was ever made regarding Fort Sumter, and Confederates gave up attempts to negotiate after less than 14 weeks!.