Doing a quick search shows the website is more than just a custom cms as the article suggests. Several other .gov.uk refer to the website with "[...]is now available at www.businesslink.gov.uk" so there must have been a huge conversion leading up to the launch. Also this quote:
It has three main types of information:
* text content explaining regulations and other areas of business [...]
* directory content
* interactive tools
£35m is still a lot for a portal but I wouldn't call it "a website".