The United Kingdom actually has one of the best fertility clinic accountability systems all over the world, and the success rates of any fertility clinic are publicly available through the Human Embryology and Fertility Authority (HFEA). When you are looking into fertility clinics and are trying to decide whether a certain clinic is the right choice for you, this is an invaluable resource. In addition to this very reliable public data, many fertility clinics also offer their own data about their success rates. The Lister Fertility Clinic has excellent success rates. When you look at the blastocyst transfer live birth rates (which they have from 2005 to 2007), the success rate for women under 35 is as high as 60 percent.
The group from 35 to 37 years old has a success rate of 53 percent, while almost half of 38 and 39 year old women end up with successful pregnancies if they choose this clinic. In the 43 and 44 year old group, this rate drops to 17 percent. What this tells you is that the clinic has success rates that are more than competent overall. Of course, there are other factors that should form a part of your decision making process, and depending on your health it is still important to ask other questions. Also see fertility clinic success rates in Europe and UK: infertility treatment options on the NHS.