United Utilities has agreed the disposal of its 15% investment in Northern Gas Networks Holdings to its other owners for a cash consideration of £85.75m. Completion of the transaction is expected by the end of 2009.The other owners are Cheung Kong Infrastructure ; Beta Central Profits, a wholly-owned subsidiary of Hongkong Electric; and SAS Trustee Corporation.Earlier this month, United sold its near 12% stake in the Manila Water Company for $73m cash.