The article is here.
It's important to appreciate that the UK has a very different court system than the US, designed to discourage lawsuits or even the "threat" of a lawsuit in demand letters, so it's not unusual that Ms. Kirkbride's first move was something other than suing the pants off of Tesco. However, it's jarring to realize that her intended profession is "fashion management" and she doesn't appear to think that she's owed compensation for the use of her image. Even if she's delighted to lend her image and chooses not to exercise her right to forbid Tesco from profiting off of derivative works based on her photo, she is still owed a reasonable royalty.
There are two lessons for us US-based artists and inventors here. First, keep your eyes peeled. Ms. Kirkbride was alerted by a fan that her image was on the shirt. Remember that having a network of people who like and/or want something from you in the industry in which you work can be priceless. Even your competitors can ultimately be allies, and it's always wise to resist burning bridges where possible.
Second, value yourself. You are on this blog because you think your ideas are worth "something." In the event that you are the unfortunate victim of copyright or trademark theft, you may be entitled to a "reasonable royalty," or actual damages. Actual damages are hard to prove after the fact, but if you are proactive and take excellent records as soon as you are alerted to the infringement, you can increase the royalty owed to you. For example, perhaps don't encourage your friends to purchase the infringing item because you think it's "cool."
As HLR follows this case, we will keep you updated as far as we can just how much a stolen image is worth when it becomes wildly popular. Tesco may end up selling hundreds of thousands of these shirts, not just because they are a global retailer, but now this story has made the shirt a hot commodity. It may be pulled from the market -- buy now, then sell on eBay! This snafu might create artificial demand. And each one of those hundreds of thousands of shirts should generate a royalty for Ms. Kirkbride.
Stay vigilant! Running internet searches on your products is the first step in finding potential infringers, but it's also important to cultivate your professional network for intel.