FlagforLondon and Flagforthecountryifyoufancy is not-for-profit.
You can use, re-use, and hack the flag for non-commercial purposes, but must attribute to FlagforLondon.uk / fftc.uk under Creative Commons Licence - Attribution - Non Commercial - ShareAlike
See - https://creativecommons.org/licenses/by-nc-sa/4.0/
Requests for commercial use of Registered Designs or copyright, contact flagforlondon.uk or fftc.uk