The power of just one trusted link has often been discussed but isn’t often proved. Normally any site that has one trusted link also has lots of others so you can never really tell which links are passing the most weight.
TV stars Richard & Judy have their own wine club that ranks very well on Google for the term “Buy wine“, the site was launched in 2005 and has just 56 links according to Yahoo. A number of the links are nofollow from Wikipedia and most are from Channel4.com. Apart from the Channel4.com links there are only about 5 others so we can be sure that their rankings are based almost entirely on link weight from Channel4.
In fact the term “buy” isn’t even on their homepage and the site still ranks for “buy wine”.