Broadcast journalist. Born in Lindi, Tanzania, the son of Scottish parents, Johnston was educated at Dollar Academy and the University of Dundee, where he read English and Politics. He completed a diploma in Journalism Studies from the University of Wales in Cardiff. Johnston joined the BBC World Service in 1991, initially as a sub-editor in the newsroom. He went on to serve as a correspondent in Uzbekistan (1993-95) and Afghanistan (1997-98), but concern was raised for his safety in 2007 when he was kidnapped in Gaza. Such was the respect in which he was held that campaigns were mounted both by Palestinians and internationally urging his release. He was eventually liberated unharmed after 114 days in captivity, returning to his parent's home in Lochgoilhead (Argyll and Bute).
Johnstone won a Sony Radio Award in 2003 for his report on how life had changed in the Afghan city of Herat since the fall of the Taliban. He was named 'Journalist of the Year' at the London Press Awards, while still held kidnapped, and awarded an honorary degree by the University of Dundee in 2008.