The Quiet Man may have become the "Angry Man" amid the plots to remove him and the allegations that he misused his parliamentary allowances to pay his wife.
But he enjoyed a joke as he prepared for a critical session of Prime Minister's Questions yesterday. "Have you seen the cover of Private Eye?" Nick Wood, his head of news and media asked. It shows the Tory leader, standing next to his wife Betsy, sipping a drink and saying: "That's funny it tastes of cyanide." Mr Duncan Smith burst into laughter.
He had an early start yesterday, arriving at his Commons office by 7.30am, and went into a meeting to prepare for Question Time, which lasted until 11am.
Over breakfast, Mr Duncan Smith and his "PMQs team" narrowed the options for his weekly joust with Tony Blair.
There was no direct discussion of the "Betsygate" affair. One obvious line of attack was the Hutton inquiry. But it was judged too risky, with some Tory MPs already describing "Betsygate" as "our Hutton inquiry".
They decided to issue a "business as usual" message by raising two "bread and butter" issues council tax and pensions. The tension showed when Mr Duncan Smith took his seat in the Commons. But he was quickly into his stride with his attack over soaring council tax, and again when he criticised Labour's means testing of pensioners. He looked happy as he sat down.
But Labour MPs cheered him as loudly as his own backbenchers, shouting "more, more" when he finished his two bursts of questions. Labour would certainly give him a vote of confidence.
In the end, "Betsygate" was not mentioned a victory of sorts for Mr Duncan Smith. "We threw the match," a Blair aide quipped. "We want to keep IDS exactly where he is."
The Tory leader headed for the Commons tea room, as he usually does, to speak to his backbenchers.
At 2.30pm he attended the Shadow Cabinet's weekly meeting, which lasted just over an hour. He made a short statement about "Betsygate". "I will fight vehemently the attacks on my character and integrity," he said.
Shadow ministers banged the table and waved their papers in support.
There was a similar rallying at the weekly meeting of Tory MPs at 5.30pm, which broke up after less than five minutes when the chairman, Sir Michael Spicer, reminded them that "the entire press corps" was outside.
After two routine meetings in his office, Mr Duncan Smith caught the train to Plymouth. Today he will be on safe territory, meeting fishermen to discuss the threat to their livelihoods from EU quotas.
One thing in Mr Duncan Smith's favour is that he has plenty of crisis-management experience. "We have been through worse than this," said one aide. But even close allies admit they do not know how "Betsygate" will turn out.Reuse content