zlacker

They are indeed Government sites! GOV.UK itself is looked after by the Government Digital Service (GDS). A brief history is available on the GDS blog: http://digital.cabinetoffice.gov.uk/about/. It's also different in that it's coded in the open. Most of the code behind GOV.UK is on public Github repositories: https://github.com/alphagov.

>>jackfr+(OP)
As another example, the app behind what powers the Design Principles, which is what this post links to, is here: https://github.com/alphagov/design-principles.