LONDON — Robert Schofield, chief executive officer of Premier Foods P.L.C., said he will retire no later than April 28, 2012. Mr. Schofield joined Premier in 2001, taking responsibility for its branded business, and was named c.e.o. in January 2002. Mr. Schofield’s retirement announcement came a day after Premier released sluggish first-quarter financials, in which year-over-year group sales and volumes were down 3.1% and 3.8%, respectively. During Mr. Schofield’s 10 years with Premier, the company completed several significant acquisitions, including the £1.2 billion purchase of RHM, formerly Rank Hovis McDougall, in 2007, and the 2006 acquisition of the U.K. and Ireland businesses of Campbell’s for £460 million. But the company in recent years has struggled to reduce debts, and earlier this year Premier sold both its meat-free businesses and its canning business for £205 million and £182 million, respectively.