Updated: PCT Fee changes take effect 1 April 2018.
The PCT system allows applicants seeking patent protection, in a number of countries, to file a single international application in English with the Intellectual Property Office.
https://www.gov.uk/government/publications/patent-cooperation-treaty-for-private-applicants
Content Reproduced verbatim from the Website of the United Kingdom Intellectual Property Office (UKIPO) as permitted under their Terms of Use.