Impellam Group plc, which ranks among the largest providers of staffing in the U.S., reported Cheryl Jones stepped down as a director of the company effectively immediately. Jones had been appointed chairman of the company in May 2009. In addition, Impellam announced Andrew Wilson will now take on the role of chairman.

Jones will work with the company over the upcoming months to facilitate the leadership transition, the company reported.

“The board very much wants to acknowledge the outstanding contribution that Cheryl has made to Impellam over the past three years,” the announcement said. “Her focus, energy and commitment have been the driving force behind the company’s transformation, which has left the group strongly positioned both in terms of operational resilience and financial strength.”

Jones appeared on this year’s Staffing 100 list.

Wilson had served as non-executive director since May 2008. Prior to that, he served as non-executive director of The Corporate Services Group plc since March 2003. The Corporate Services Group combined with the Carlisle Group Ltd. in 2008 to form Impellam.

Impellam Group ranks No. 45 on Staffing Industry Analysts’ list of largest U.S. staffing firms based on 2011 U.S. staffing revenue of $272 million. In addition, it ranks No. 19 on the Staffing Industry Analysts’ list of largest global staffing companies with $1.82 billion in 2011 global staffing revenue.

The company conducts business primarily in the U.K. and North America, with smaller operations in Australia, Ireland, New Zealand and mainland Europe.