Corporal Palmer was one of the UNIT soldiers stationed at Tulloch to investigate the destruction of nearby oil rigs. (PROSE: Doctor Who and the Loch Ness Monster)
While giving reports to Brigadier Lethbridge-Stewart, the Zygons used nerve gas to knockout the villagers and the UNIT personnel to stop them from seeing the Skarasen when it was crossing the moor.
When the Fourth Doctor, Sarah Jane Smith, RSM Benton and Huckle arrived, they revived the Corporal, the Brigadier, and the rest of the soldiers. He was later stationed at the radio, where he helped the Brigadier trace the location of the Zygon spaceship to Loch Ness. (TV: Terror of the Zygons)