LONDON--Barclays PLC (BARC.LN), a global financial service provider, said Thursday that David Walker has been appointed as a non-executive Director of Barclays with effect from Sept. 1, and will succeed Marcus Agius as Chairman of Barclays with effect from Nov. 1. MAIN FACTS: -Marcus Agius will step down as a Director and as Chairman of Barclays with effect from Oct. 31. -David Walker is currently a Senior Adviser to U.S. bank Morgan Stanley International, having previously held the position of Chairman. -Barclays PLC shares closed Thursday at 178.9 pence, valuing the company at GBP21.89 billion. -Write to Razak Musah Baba at razak.baba@dowjones.com Subscribe to WSJ: http://online.wsj.com?mod=djnwires