I have just recently come across another reason to change or add a surname. Burke's Landed Gentry 1899 edition (on Google Books) mentions the following (not Portsmouth area) name change: "Mr. H. H. PHILLIPS-CONN is the 2nd son of the late Major Michael PHILLIPS, J.P. of Glenview, co. Cavan (see that family), by Mary Anne his wife, and dau. of the late Highgate TENCH, of Ballybealy House, co. Wexford, Heir to the Mount Ida estates in 1893, on the death of his uncle by marriage, the late John Lambly CONN, and, in accordance with his will, assumed by Royal License 4 July, 1894, the additional surname of CONN." "Mr. CONN devised his estates to his wife's nephew, Highgate Henry PHILLIPS, who has assumed by Royal License the additional name and arms of CONN." So the reason for the Royal License was to assume the arms of CONN (which are described heraldically in the same article.) When you see a hyphenated surname, this may involve some paperwork, or it may not, depending on the purpose of the name change. HTH Martin Willcocks Taylorsville, UT, USA.