Grice joined HM Civil Service as a Fast Stream trainee in 1985, when he took up a position in the Department for Transport. Two years later, he moved to the Department for the Environment. In 1992, he transferred to the Scottish Office Environment Department. He was head of the Housing and Urban Regeneration Branch between then and 1995, when he was appointed head of management and change. He was appointed head of the Constitution Group in 1997, where he was involved in leadership roles relating to the legislation for and organisation of the 1997 Scottish devolution referendum. He was appointed Director of Implementation for the Scotland Bill in 1998 and was responsible for establishing the new Scottish Parliament's organisation.