Diamond Transmission Corporation Limited

Diamond Transmission Corporation Limited (DTC) is a UK-registered electricity transmission company and wholly‑owned subsidiary of Mitsubishi Corporation. Incorporated in April 2013, it has operated as Mitsubishi’s European transmission business management company, consolidating and managing the group’s investments in the European transmission sector. The company functions as Mitsubishi’s power transmission hub in Europe, focusing on undersea power transmission systems that transport electricity generated by offshore wind farms to onshore high‑voltage grids. DTC reported revenues of around GBP 1.1–1.5 million in recent years and held net assets of approximately GBP 190 million as of March 2024, with a small in‑house team supported by wider group resources. Operationally, DTC’s role is primarily that of a holding and investment platform for a portfolio of UK offshore transmission owner (OFTO) businesses. Through its Diamond Transmission Partners structure and other subsidiaries, it owns or has owned interests in multiple OFTO licensees connecting major UK offshore wind farms, including Beatrice, Rampion, East Anglia One, Walney Extension, Dudgeon, Galloper and Hornsea One. These regulated OFTO entities own and operate offshore substations, export cables and associated onshore substations, transmitting green electricity from large offshore wind farms into the onshore transmission system under long‑term licences. DTC typically partners with infrastructure investors such as HICL Infrastructure and utilities including Chubu Electric Power in these project vehicles. In December 2024 Mitsubishi significantly reduced DTC’s share capital, and in early 2025 DTC entered members’ voluntary (solvent) liquidation, with its offshore transmission activities continuing through the underlying OFTO companies and related platforms.