Slaughter and May and Haiwen & Partners are advising British alcohol giant Diageo PLC on a complex deal in which it aims to become controlling shareholder in one of China’s best-known liquor brands.

More than a year after its bid was first announced, Diageo, which owns brands including Johnnie Walker whiskey and Smirnoff vodka, has received approval from Chinese regulators to increase its stake in Sichuan Chendu Quanxing Group Co. Ltd. to 53 percent from 49 percent, for $22 million.