Ashbel Williams couldn’t resist the lure of public service — or the opportunity to flee the carnage on Wall Street — so he is heading back to his home state. On October 20, Williams, 53, returns to the post he held from 1991 to 1996: executive director of the Florida State Board of Administration. Most recently, Williams was managing director of investor relations at New York hedge fund Fir Tree Partners. Before that he spent four years at Schroder Capital Management, where he last served as president. The Florida State Board, with $155 billion in assets as of the end of June, includes the Florida Retirement System, with $130 billion. It’s unique among public pension funds in that the executive director, rather than a board of trustees, holds most of the investment authority. Plus, 40 percent of the assets are managed internally. “In the financial world the opportunity to act decisively is two thirds of the battle,” says Williams.