Before a large amount of redevelopment in this area, there was a street called Granville Street. The street was officially named at a meeting in 1869. "The committee have granted permission to Mr. James Dunn to name a new street off Leeson Street and Grosvenor Street 'Granville street', also to Mr. Peter Quinn to same a new atreet off Shore Strand 'Arundel Street.' report: Belfast News-Letter - Tuesday 02 March 1869. The Belfast And Province Of Ulster Directory 1870 indicates people already living there as well as a section of vacant ground which goes to show the street is still being developed. It is possible Granville Street as was got its name from Granville George Leveson-Gower, 2nd Earl Granville, (11 May 1815 – 31 March 1891) who was a prominent politician in the 1860s. “Granville did succeed in re-establishing good relations with America which had been strained by the Civil War”.
https://www.gov.uk/government/history/past-foreign-secretaries/george-gower.