Prime Minister of Thailand Rajanubhab took over this role. In fact, the office most considered the precursor of that of the prime minister was the ancient office of "Samuha Nayok" (สมุหนายก), which was run by an "Akkhra Maha Senabodi" (อัครมหาเสนาบดี) or "chief minister in charge of civilian affairs". The first Prime Minister of Siam was Phraya Manopakorn Nititada, a judge. The title of the office was changed from "Prime Minister "of Siam"" to "Prime Minister "of Thailand"" in 1945 and then permanently with the renaming of Siam to Thailand in 1949. For most of its existence the office has been occupied by Army leaders;
Acting prime minister Acting prime minister An acting Prime Minister is a cabinet member (often in Westminster system countries) who is serving in the role of Prime Minister, whilst the individual who normally holds the position is unable to do so. The role is often performed by the Deputy Prime Minister (where that position exists), or by another senior Minister. The office is commonly used when the Prime Minister is absent from the territory of that nation, when the Prime Minister is in ill health or, on maternity leave. An acting Prime Minister should be distinguished from a caretaker Prime Minister, which refers