Pembrokeshire was a parliamentary constituency based on the county of Pembrokeshire in Wales. It returned one Member of Parliament (MP) to the House of Commons of the Parliament of the United Kingdom, elected by the first past the post system.

Sir John Perrot was a member of the Welsh gentry who served as Lord Deputy of Ireland under Queen Elizabeth I of England during the Tudor conquest of Ireland. It was formerly speculated that he was an illegitimate son of King Henry VIII, though the idea is rejected by modern historians.Sir John Perrot, was a figure of unusual power and influence in Tudor Britain and Ireland. Born near Haverfordwest in 1528, he inherited wealth and power – the Perrots had been accumulating both in west Wales for centuries – and gained more ingratiating himself with the English court. His own son described him as a "very cholericke" man, who "could not brooke any crosses". He had already gathered many offices by the time he was sent to Ireland in 1571 as President of Munster to suppress a rebellion. His methods were characteristically violent – he hanged over 800 of the rebels – but he resigned after two years, having failed in his mission.Back in west Wales he contented himself with self-enrichment and self-glorification, rebuilding in grand style his two main homes, Carew Castle and Laugharne Castle. He returned to Ireland as 1584 as Lord Deputy, with the task of crushing the Irish and colonising their land. Again unsuccessful, he returned, was falsely accused of treason by his many enemies, and died in the Tower of London in 1592, possibly of poisoning.