Who is Christopher Steele, author of the explosive Trump Russia dossier?

Christopher Steele, who wrote reports on compromising material Russian operatives allegedly had collected on US President-elect Donald Trump, is a former officer in Britain's Secret Intelligence Service, according to people familiar with his career.

Former British intelligence officials said Mr Steele spent years under diplomatic cover working for the agency, also known as MI6, in Russia and Paris and at the Foreign and Commonwealth Office in London.

His colourful life as an MI6 spy took him from Russia to Afghanistan via Paris, before the wife with whom he shared it died at the tragically young age of 43, it has emerged.