Scientists then went on to solve the mystery of Louping Ill which was found to be caused by a virus transmitted by ticks and a vaccine was soon developed.

While developing a vac-cine against another sheep disease called Louping Ill, Gordon unwittingly pre-pared the vaccine using tissues obtained from sheep that had grazed on pasture previously occupied by scrapie-infected sheep.

In the 1920s Louping Ill and Braxy claimed almost a third of the lambs born in Scotland and Grass Sickness was having a devastating effect on horses, which were used for heavy labour on farms at that time.