There are "lies, damned lies and statistics". Few government figures are more closely examined and inventively interpreted than the annual Statistics of Scientific Procedures on Living Animals.

To the disappointment of critics of medical research on animals, the numbers are down a little this year. But the relative increase in work on the emotively described "harmful genetic mutants" will still provide fuel for those who promote the myth that researchers are sadistic.

Since the sequencing of the human genome, the funding of medical research in Britain has more than doubled. This reflects the pace of progress, especially searching to find the genetic contribution to incurable human diseases and using that information to discover how they might be treated.

Only a fraction of medical research involves animals. If funding has doubled, it's not surprising that the number of experiments on animals has also recently increased. But the overall rise in animal use over the past decade has been about 50 per cent, compared with more than a 100 per cent increase in total expenditure on medical research. In my statistics book, that's a dramatic decrease.

Moreover, since researchers who use GM animals have to report not just the ones involved in experiments but every animal that is born, the numbers of those in the annual statistics are artificially inflated, compared with non-GM animals.

Since GM animals have been an increasing proportion of the total over the past few years, the actual number of animals on which any experiment has been carried out, compared with the total money spent on research, has been falling.

And what of the criticism that GM causes suffering in the mice and is also a useless model of human disease? An animal with a disease truly comparable to that of a human is bound to have symptoms similar to those of the human patient. GM technology has produced animals with diseases remarkably similar to human conditions for which there was no previous animal model – and hence little chance of progress in understanding the disease.

We now have mice with Parkinson's disease, Alzheimer's, Motor Neurone Disease and Muscular Dystrophy, even though mice don't normally have those diseases. Research into those horrific conditions has been transformed and patients suffering from these disorders have new hope.

The writer is Professor of Neuroscience at the University of Oxford and a former chief executive of the Medical Research Council