 Kingston had appointed Playford as Treasurer in his government, however in 1894 Playford moved to London to act as Agent-General for South Australia before returning to South Australia in 1898 to serve in Kingston's government from the 1899 election as member for Gumeracha, until he crossed the floor in later that year over a potential erosion of the power of the Legislative Council, bringing down the Kingston government in the process.He also found the time to involve himself in the planning of the Federation of the Australian Commonwealth and drafting the Australian Constitution.As part of this, he proposed the title "Commonwealth of Australia".