The Vivien Law Prize is offered annually by the Henry Sweet Society for the best essay in the history of linguistic ideas. The competition is open to all currently registered students, and to scholars who have received their PhD or equivalent qualification within the last five years. Essays can be up to 8000 words in length. Closing date is 31 October 2015 (extended from 30 September 2015).
Further information is available here: http://www.henrysweet.org/grants-and-prizes/vivien-law-prize/