Oil and gas engineering service business Plexus Holdings has extended a contract with Centrica North Sea Gas in a deal worth up to 850,000 pounds.Plexus has agreed to supply the gas production arm of the owner of British Gas with supply extra drilling equipment for the GROVE 49/10a-4 (G1) production well in the southern North Sea.It expects revenues to begin in the first quarter of Plexus' 2014 financial year.Plexus Chief Executive Ben van Bilderbeek said: "This contract win is a significant milestone for Plexus as it continues to expand its wellhead offering from exploration drilling into the larger and more lucrative production market."