What.. Are these government sites? Those do not look like such as they are too clean and positive. Are you sure they're just not a victim of very stylish hacker?
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.
