He became the first President of the Board of Agriculture in 1889, with a seat in the Cabinet, and retained this post until 1892. In the Conservative Cabinet of 1895 to 1900 he was President of the Local Government Board, and was responsible for the Agricultural Rates Act 1896. However, he was not included in the ministry after its reconstruction in 1900. Salisbury offered him a peerage, which he declined. Chaplin was considered an authority on agricultural matters and he served on the Royal Commission on the Supply of Food and Raw Materials in Time of War (1903–1905), the Royal Commission on Housing and the Royal Commission on Horse Breeding. He was also president of the Old Age Pensions Committee.