The link: command in Google is not very accurate. If you sign up for webmaster central you will get better information or use yahoo linkdomain: command. If you just search for your domain with quotes you will only get pages that have that actual text on them not what is in the href="". Sometimes you will see pages in that search that are linked to with the domain as the anchor text.
These pages are pages that contain links to www.domain.co.uk, but the text "www.domain.co.uk" does not necessarily appear on the page. The anchor text might be "Great Widgets" or "interesting site," or, it might be "www.domain.co.uk". Not all links display the actual domain name.
Keep in mind that Google generally returns results for text on the page, not for underlying code.
Find web pages that contain the term "www.domain.co.uk"
Here, "www.domain.co.uk" appears as visible text on the page. There may or may not be an actual link involved.