Confusing, There are five William [various middle initial] May on the 1881 census in the Royal Navy, two would fit.
The Newspaper give us a birth date 1859/60 Living Coverock Cornwall a Antique Dealer. The 1881 Census William B May b.1858 White Zeal Glouster, HMS Tamar RMLInf, there is no May Royal Marine on the Medal Roll. William May b.1860 Folck Cornwall, HMS Curacao RN able seaman.
1891 Census address Coverack Village St Keverne Helston Cornwall Married to Mary, he born 1859 Chacewater Cornwall, 1911 census address Coverack St Keverne, m to Mary 2 kids, He is a Fisherman. The 1939 people index, William R May born 25 March 1859, married to Elizabeth, Antique dealer, Luxulyan Kerrier, Cornwall. Only death that fits, William R May, born 1860 died May Qtr 1956, age 96, Kerrier District, Cornwall.