Seymour Dunn was responsible for laying out many golf courses, particularly in continental Europe and in New York state (after emigrating to the USA). His best known work includes, but is not limited to:

BELGIUM:
Royal Ardenne (1900; full name: Royal Golf Club du Château Royal d'Ardenne) / Royal Belgique, Ravenstein, Brussels (1905) / Royal Ostend (1903).

UNITED STATES:
Craig Wood G&CC, NY (1926) / Lake Placid Club, NY (1909, Links course) / Laurel CC, MS (1919; the oldest course still being played in Mississippi) / Locust Hill CC, NY (1927) / Saranac Inn G&CC, NY (1910, with his uncle Willie Dunn Jr) / Ticonderoga GC, NY (1929) / Tuscarora GC, NY (1923).

According to his birth certificate Seymour Dunn was born on the West Links, North Berwick. As the only building on the golf course was his father Tom's club-makers workshop, the assumption is that he was born in the timber building beside the first tee. Described as 5'11", with fair hair, blue eyes, and a thistle tattooed on his forearm, Seymour was 15 years old when he first visited the USA in 1897. During that visit he laid out a nine-hole course at Lawrenceville School in New Jersey.

In 1899 Seymour became the golf professional at the Société de Golf de Paris. During his time there he laid out several courses in continental Europe, not least three of the Belgian "Royals," as well as a course for King Emmanuel of Italy and one in the Rothschild Estate, France.

1904 saw Seymour becoming the pro at Royal County Down GC in Northern Ireland. In 1906 he spent the summer at Lake Placid, New York, an area he would be associated with for much of his career. He permanently emigrated to the USA in 1907, joining his uncle Willie Dunn Jr at Van Cortlandt Park GC, and subsequently becoming the pro at the Wykagyl GC, Rochelle, NY, and then Lake Placid Club (1908-26). In his time at Lake Placid he was also briefly the golf professional at Laurel CC (Mississippi).

Seymour set up a mail order company distributing golf equipment, while also making his reputation as a leading golf instructor of the time. He wrote the best-selling "Golf Fundamentals - Orthodoxy Of Style," with top professionals like Jim Barnes, Walter Hagen and Gene Sarazen benefitting from his personal instruction. Ben Hogan later acknowledged Dunn's swing theories in his own book "The Modern Fundamentals." In 1929 Seymour set up an Indoor Golf School in Madison Square Gardens with thirty instructors and eighteen pitch and putt holes. His contribution to the evolution of the game continues to be acknowledged.