J.P. Morgan
Although the Titanic was built in Belfast, Ireland and registered in Liverpool, England, it was actually owned by the White Star Line, which was a part of IMM (International Mercantile Marine) corporation, owned by American financier: J.P. Morgan. Another interesting fact is that J.P. Morgan was supposed to travel on the Titanic’s maiden voyage but canceled at the last minute because of illness. He died shortly after the Titanic tragedy in 1913.
The Titanic, One Century Later 
The ship was indeed constructed at Harland and Wolff in Belfast, Northern Ireland which was and still is a part of the United Kingdom of Great Britain and Northern Ireland. Its port of registry was in Liverpool, England. However against the assumption that White Star Line were a US company, in fact White Star formed in Liverpool, England in 1845. They were a British company. 10 years prior to the maiden voyage of the Titanic, White Star was made a part of the International Mercantile Marine Co., an American shipping conglomerate, but were never take over by them. Think todays Airline conglomerates whereby international carriers buddy up to share flight routes, but each are still independent. Anyway, 22 years after the sinking of the ship, White Star Line partnered up with Cunard Line, a Southampton, England based company forming Cunard-White Star Line, Ltd which was based in Liverpool. So in fact White Star was always a British based and formed shipping company which partnered under an American managed shipping conglomerate. So to answer the question, the Titanic was most definitley a British owned ship built in the UK, with UK cash, which became part of an American shipping conglomerate; nonetheless Titanic was very much a British ship.
Interesting…Thank you for the detailed explanation.