Latest: Queen Elizabeth to send message to widow of Martin McGuinness

Latest: Donald Tusk, President of the European Council, said: "Sad to learn of sudden passing of Martin McGuinness. His contribution to peace in Northern Ireland will endure."

Update 1.05pm: Donald Tusk, President of the European Council, said: "Sad to learn of sudden passing of Martin McGuinness. His contribution to peace in Northern Ireland will endure."

The European Council president tweeted: "Sad to learn of sudden passing of Martin McGuinness. His contribution to peace in Northern Ireland will endure.