Here is an excerpt from the post:
With legislation.gov.uk we aimed to open-up access to the government’s legislation database, by creating an API first. The legislation.gov.uk API allows anyone to access the data we hold in the database, or to use the services we have built, such as the search or to dynamically create PDF documents from the data. We wanted to show that government could create a high-quality, technically sophisticated API, following the principles of both REST and Linked Data. We also wanted our API to be fully open, with no restrictions on use, and no need to register before using it.
We developed the API and then built the legislation.gov.uk website on top of it. The API isn’t a bolt-on or additional feature, it is the beating heart of the service.
For more information, please see the complete post.