These whistles were used by William Neill while serving in France and Flanders and, later, as a Special Constable. All were made by J Hudson and Co., then the premier whistle making company in the United Kingdom and now, as Acme Whistles, the world’s largest whistle producer.
The brass whistle is the Acme Thunderer and was commonly used during the First World War. Over 200 million of these whistles have been sold.
The silver coloured whistles are the Metropolitan police whistle, registered as a trademark by Joseph Hudson in 1884. One is stamped Royal Irish Constabulary and the other is stamped Royal Ulster Constabulary. This whistle was also used during the First World War and its sound is instantly recognisable.
More can be read about the Metropolitan whistle here.