Iain Duncan Smith's bearing shows that he comes from a military background. The former Scots Guards captain is quiet, assured and, when the occasion arises, passionate - particularly in his Euroscepticism.
His mother was a ballet dancer and his father a group captain in the RAF, serving as a fighter pilot in the second world war. Duncan Smith himself saw active service in Northern Ireland before becoming assistant to General Sir John Ackland during the negotiations between the British government the white UDI-ers over then-Rhodesia between 1979-1981.
The government's decision to take a leading role in the European rapid reaction force provoked furious attacks from Duncan Smith - though to little avail with the public, with opinion polls suggesting they were relaxed on the subject.
An active Christian, colleagues regard him as one of the most thoughtful, even intellectual, figures in the party. But despite - or maybe because of - this, Duncan Smith is generally held to be difficult to warm to. Very clever but stand-offish and stiff with it, supporters concede.