Professor Derek Knottenbelt is a well known veterinary expert. He holds a personal Chair in Equine Medicine at the University of Liverpool. He has written widely about equine medicine. He received the Animal Health Trust Scientific Award in 2003, the BEVA (Blue Cross) Welfare Award in 2004 and the OBE in the Queen's Birthday Honours of 2005 for his services to Equine Medicine.

It is important in science that conclusions are based on evidence. The Nobel Prize winning physicist Professor Richard Feynman sums this up in a famous quote during one of his recorded lectures. He was talking about the derivation of knowledge about the laws of physics but the principle applies to all of science. “If it disagrees with experiment, it is wrong. In that simple statement is the key to science. It doesn't matter how beautiful the guess is. It doesn't matter how smart you are. Who made the guess . What his name is. If it disagrees with experiment, it is wrong. That is all there is to it.” It is important in science to remember that it is the evidence that substantiates that someone is correct not their qualifications or their reputation. Therefore to be scientific we should take note of someone's qualifications and background but it is only the evidence that shows whether they are correct or not.

Professor Knottenbelt is also well known as an anti-ragwort campaigner. His views seem rather forthright and he is quoted in several places as saying about the subject of ragwort "It is toxic to humans, so what the hell are we doing with it in this country?"

He is frequently described by the horsey lobby as a leading expert on ragwort. Professor Knottenbelt is undoubtedly a very fine veterinary expert, but the study of ragwort is a botanical matter and requires knowledge of botany and ecology. These are not veterinary matters covering animals and the evidence seems to clearly suggest that a lot of what he is saying is incorrect. The articles here set what he is saying in the context of the available research and information. He has played quite a role in the public perception of ragwort and it is therefore clearly in the public interest that his views are examined in relation to the scientific and other evidence so that people who are looking at what he says are properly informed of the weaknesses in his arguments in order that they can form an objective judgement on the issues surrounding ragwort.

To start this analysis we should first examine primary sources of information that we can attribute directly to him personally. These are things written by him alone and not press quotations.

Firstly there is an article in the newsletter of the Friends of Bidston Hill. See:- Professor Derek Knottenbelt - Bidston Hill. This contains clear inaccuracies about the law and apparent misunderstandings of the ecology of ragwort.

Secondly, there is a letter he wrote to the Yorkshire Post. See:- Professor Derek Knottenbelt Yorkshire Post. This contains a number of claims on the occurrence of ragwort, examples of claimed poisoning in humans, which the evidence seems to show were caused by different plant, and , most importantly, the statistical basis on which he bases his claims of large numbers of horse deaths. These statistics do not appear to be accurate and do not appear to be based on proper scientific principles.

Thirdly, there are articles he wrote for a Conference on Feeding horses See:- Professor Derek Knottenbelt Feeding horses. These contain similar claims to the other items and more detail, it would appear that the professor is mistaken about a number of matters involving the biochemistry and the toxicology of the plant and that as a consequence he apparently over estimates the risk of small doses. It would also appear that he is unaware of the areas of science which go beyond pure veterinary science which explain why animals are reluctant to eat the fresh plants.

In addition there is also a list of Professor Knottenbelt's comments and quotations in the press