Have you heard of Ahmad Noor? Perhaps you knew him as Halaloedin Hamzah?
He was a Mandailing from the Dutch East Indies who free-lanced for Kompas in the early days of his career. He fled and sought refuge in Malaya, when the Dutch authorities cracked down on railway strikers in 1929, in which he was involved, and staged a mass arrest. He later changed his name to Ahmad Noor Abdul Shukor, and had a short stint with Saudara in Penang. (read more here)
The picture (taken from the Kinta Valley book) isn’t that clear…but I believe Ahmad Noor is probably the gentleman standing in the middle.