 Complete the following phrase:  Henderson was a keen supporter of the Republican cause and anti-fascist forces during the Spanish Civil War. He joined the Spanish Medical Aid Committee SMAC when it was first established in 1936, and later travelled to Spain to visit numerous front-line hospitals. During the war, Henderson donated his Rolls-Royce car and had it converted into a makeshift ambulance to serve republicans and anti-fascists. This ambulance saw frequent use and was in action during the 