I have always thought that in order to increase page rank you need to get plenty of sites linking back to yours, the higher the page rank of the site linking to your site the better! There seems to ba an exception to the rule- www.premiergranite.co.uk It has only a few links that I can see and it has a page rank of 5
it seems to show a 5 and then redirect to index.php which is a 3. anyway, there are a lot of reasons why this could happen. 1) there was a visible backlinks update but not a visible pagerank update-- ie, the "old" pagerank is showing 2) not all links show in google's link:site.com command. you can have PR while having nothing showing up in a link:site query. 3) you may be checking the backlinks of domain.com/index.php rather than domain.com in this example; domain.com is what appears to have the PR5.