In 1967 Bill Siddons was drafted to be 'the doors' roadie at 18 and 6 months later, at 19, was promoted to manager. He spent the next few years learning what that meant- especially considering his primary responsibility was Jim Morrison. 4 years later, after he buried Jim in Paris, he continued to represent the remaining 3 'doors' for 2 more albums and tours through 1972. In 1974 he went to work for Elliot Roberts at David Geffen's request and represented America, the Band and Souther Hillman Furay for Lookout. When Peter Golden called and suggested Van Morrison needed someone, bill chose to leave and take over Van for the next couple years. Bill and Peter formed a partnership in1979, signing Poco, David Lindley, Crosby Stills Nash, Jackson Browne, and others. Peter retired in 1985 and Bill continued to represent CSN until 1996 and also handled Robert Palmer for the "Addicted to Love" cycle (2 number one singles, small hall tour of the year), and got him signed to EMI. He also signed the Darling Buds on Sony, and got them a # 1 single at Alternative Rock radio. He signed Pat Benatar in '96, resulting in her #1 single on AOR. In '99 he consulted Pollstar Magazine and website, set them up to sell merchandise on their highly trafficked site, and subsequently produced their annual awards show for a few years.

In 2003 he formed a partnership with Howard Lapides (he thrived in partnerships and his client, Elayne Boosler needed someone with some experience in comedy). Howard runs the TV wing of the Core, representing Dr. Drew and others. A meeting with Toni Profera resulted in her becoming part of the Core in 2003, bringing years of experience in the retail, publishing and marketing to the Core. Toni brought a business development wing to the Core and is integrally involved in the online component of Core's services and has become a partner.