Jeffrey Ash was the son of Ingram Ash, one of the owners of Blaine-Thompson, the dominating Broadway advertising agency during the post-WWII years. By some accounts, the firm at times represented 90 percent of the shows on Broadway. After graduating from Muhlenberg College in 1967, the younger Ash began work at Blaine-Thompson alongside his father, handling the advertising for such legendary producers as Harold Prince, Stuart Ostrow and Alexander H. Cohen.