Walsh's great-great-grandfather was Reverend Philip Walsh who was the Prebendary of Tipperkevin, Vicar of Blessington, Rector of Ballymore Eustace, and chaplain to Primate Michael Boyle, Archbishop of Armagh. His mother was Augusta Junietta Thwaites and his father was Irish born Lieutenant William Walsh of the 7thRoyal Fusiliers. Walsh was born in 1836. In 1865 he married Catherine Banchory Pickering, daughter of Agnes Norris and General W. H. Pickering. Catherine and William Walsh had two children: William Trevor Hayne Walsh who was an educationist, and Leslie Herbert Walsh who became a surgeon.
Career
He was educated at St Alban's Hall, Oxford where he graduated B.A. in 1859 and M.A. in 1862. He was ordained deacon in 1860 and priest in 1861. In 1891 he was awarded the honorary degree of Doctor of Divinity at Oxford. Walsh began his ecclesiastical career with a curacy at Horsell from 1860 to 1863 and was curate of Upper Chelsea from 1863 to 1865. For a period from 1865 to 1870 he was Secretary of the Church Mission Society for Kent, Surrey and Sussex. This was followed by a three-year period as Superintendent of Missionaries and Clerical Secretary of the London Diocesan Home Mission, a role that he undertook again from 1886 to 1890. He was perpetual curate of St. Andrew's Watford from 1873 until 1878 and chaplain in Rome from 1878 to 1879. Walsh became Vicar of St MatthewNewington from 1879 to 1886.
Mauritius
He became mission chaplain to the Bishop of London from 1898–1891. Temple also made him a Prebendary of Wedland in St Paul's Cathedral from 1889–1891. He was consecrated Lord Bishop of Mauritius in Westminster Abbey on 2 February 1891. Just over a year later, one of the worst cyclones ever to hit Mauritius occurred on 29 April 1892 and devastated Port Louis. The Anglican Cathedral of St James was one of the few buildings that remained standing and was used as a hospital.
Walsh died on 27 October 1918 at his home in Chillenden Chambers, in the Precincts, Canterbury; the funeral was held in the Cathedral and the interment at St Martin's Church. Walsh's wife, Catherine, died in 1915. The Canterbury Cathedral Oblations Book of 1919–1926 records the unveiling, by the dean of the cathedral, of a memorial tablet dedicated to Walsh. This is in the north transept next to the tablet for Canon Danks D.D. It was unveiled on 5 May 1921 and bears the six Arms of Oxford University, of Merton College, of the See of Canterbury, of Christ Church Cathedral, of Mauritius and the Cinque Ports of which Canon Walsh was chaplain.