As a very young boy Harrison showed an outstanding gift for drawing, and his later sketch books reveal a rare talent for accurate observation and draughtsmanship.

He was a genuine artist working in the field and had the ability to capture the movement and life of the birds perhaps better than any other artist.
For many years Harrison lived and worked in Norfolk where he was a keen supporter of the Norfolk Wildlife Trust. He studied at the Slade School and improved his knowledge of anatomy through the practice of taxidermy.
He has illustrated many books and has held numerous exhibitions at the Tryon Gallery.

Aylmer Tryon, the founder of the Tryon Gallery shared the opinion with others that Harrison's birds in flight surpassed even those of Archibald Thorburn.