The Light Railways Act of 1896 had been enacted in order to permit the construction of local railways with some of the requirements for main line routes somewhat relaxed, to allow cheaper construction, and the G&SWR belatedly considered that the Cairn Valley line was well suited to the arrangement. Some changes to the route were suggested by them at this stage, but they were advised that the Act authorising the line could not be varied without a further Act of Parliament. Inaction followed until the Board resolved to apply for a Light Railway Order (LRO) for the originally determined route, on 4 October 1898; the budget was reduced to £123,857. The official process of approving the LRO was not swift, and it was finally ratified on 29 December 1899.