A good button whistle made by Hudson and marked with their trademark name, 'The Acme'. These large whistles are loud and many were used by the railway, police and the military, who knew them as the 'Thunderer'.This example retains its original pea, as well as most of its original finish, with no sign of repair. It also bears a patent number dating to 1924, which is when Hudson introduced this new design of lanyard attachment.A very usable antique of Scottish interest.