Somewhere around the first half of the 20th century Generation Flageolets, better known as tin whistles, were born. They and Clarke tin whistles were just about all you could find in music shops until the last decade or so. Even still, the two brands gave whistle players a choice, Clarke for a super chiffy tone and Generation for a clear singing tone.
Even with all the whistles that are available today, many traditionalists prefer Generations to other pennywhistles as they feel that the sound is more connected to the tradition. One of the most influential players that helped to establish that traditional sound is Mary Bergin. She played Generations in various keys to great effect on her albums Feadóg Stain I and II.