Question: How long does the prime minister which has Sarla Grewal as the principal secretary serves?
Sentence (from "Secretary of State for Northern Ireland"): Her Majesty's Principal Secretary of State for Northern Ireland, informally known as the Northern Ireland Secretary (Irish: "Rúnaí Stáit Thuaisceart Éireann" ), is the principal secretary of state in Her Majesty's Government with responsibilities for Northern Ireland.
Relevant evidence: No