https://www.gov.uk/government/news/uk-and-japan-to-develop-future-fighter-jet-engine-demonstrator
>The UK and Japan have also agreed a ‘Memorandum of Cooperation’ which enables both nations to pursue joint technologies.
>this work will be undertaken by the Team Tempest industry partners: BAE Systems, Leonardo UK, MBDA UK and Rolls-Royce.

英国との共通化の分析や技術協力は直接契約でなく両国当局間の覚書によって実施、エンジンについて英はRR、日はIHIを担当として両国間検討を詰めていくんんじゃないんすかね