Viscount St Davids, of Lydstep Haven in the County of Pembroke, is a title in the Peerage of the United Kingdom. It was created in 1918 for John Philipps, 1st Baron St Davids. The Philipps family descends from Sir John Philipps, who represented Pembrokeshire in the House of Commons. In 1621 he was created a Baronet, of Picton Castle in the County of Pembroke, in the Baronetage of England. His grandson, the third Baronet, also sat as Member of Parliament for Pembrokeshire. He was succeeded by his son, the fourth Baronet. He represented Pembroke and Haverfordwest in Parliament. His son, the fifth Baronet, sat for Haverfordwest. He was succeeded by his younger brother, the sixth Baronet. He represented Carmarthen, Petersfield and Pembrokeshire in the House of Commons.
His son, the seventh Baronet, was Member of Parliament for Pembrokeshire and Haverfordwest and also served as Lord-Lieutenant of Haverfordwest and of Pembrokeshire. In 1776 he was raised to the Peerage of Ireland as Baron Milford. However, this title became extinct on his death in 1823. He was succeeded in the baronetcy by his distant relative, the eighth Baronet. He was a descendant of Hugh Philipps, third son of the first Baronet. He was succeeded by his younger brother, the ninth Baronet. This line of the family failed on the death of the latter's son, the tenth Baronet, in 1857.