Built in South Korea. Although:
"Despite being built in Korea, the UK has won £150m of associated contracts to assist the project.
These include £90m on UK contracts for equipment, systems, design and support services.
There will be a further £60m investment in the UK to be spent on customising the ships for the Royal Navy, trials and specialist engineering help"
BBC News - South Korea wins Royal Navy tanker deal worth £452m
UK firms took part in the tender, but the Ministry of Defence (MoD) said none made a final bid to take part.