No. 54 Hospital in Wimereux was one of the Base Hospitals known as "London General Hospital" and was in operation from July 1917 until May 1919.
You can find a comprehensive description of the Base Hospitals in France and elsewhere during the First World War, by following the link http://www.1914-1918.net/hospitals.htm
Rosaleen's poem "The Smells of Home" was first published in "The Spectator" on 30th November 1918 and is included in "The Winter of the World Poems of the First World War", edited by Dominic Hibberd and John Onions, published by Constable and Robinson Ltd., London, 2007.
My grateful thanks to The Red Cross.