Mr Barker may be right: It is possible that plants have sensitivities that we do not yet understand.
However, we know for sure that animals have well-developed nervous systems and pain receptors the same as humans. Like us, they show pleasure, fear and pain.
Moreover, when we eat animal products, we consume many more plants indirectly than if we ate those plants directly.
This is because farm animals have to be fed huge quantities of grasses, grains, soya and seeds to be converted into meat. It can take up to 15lbs of plant foods to produce 1lb of meat.
As a vegetarian you cause fewer beings (animals and plants) to suffer and die for you.
The evidence that animal farming is a large contributor to global warming is overwhelming.
In addition, rearing farm animals is extremely inefficient: It uses a huge proportion of our land and contributes to soil degradation, dwindling water supplies and air pollution. Far less land, water and energy is needed to feed vegetarians compared to meat eaters.
I'm not sure how many people Mr Barker thinks are too many, but there are more than three times as many farm animals in the world as there are people.
The demand for meat is causing the livestock population to expand at a much faster rate than the human population.
Breeding animals in these numbers is not part of the natural cycle and is contributing to all the environmental problems already outlined.
I have chosen to be vegetarian, not only because I want no part in animal suffering, but it is also a positive step in helping to feed the world and lower my environmental impact.