What began as a throw-away remark looked set to reactivate the protest against excessive pay in privatised boardrooms and fuel renewed calls by the Labour Party for industry regulators to have new powers.
Andrew Smith, shadow chief secretary to the Treasury, said: "This crass remark shows how badly out of touch privatised utilities are and how out of touch the Government is for failing to take the action Labour has called for."
Sir Iain told the Employment Select Committee he worked a 70 hour week for £663,000 a year - plus £94,000 pensions contribution - and regarded it a "fair and just" remuneration.
Asked to reflect on his controversial reference, he agreed it was a "flippant" remark. "I work long hours which is precisely what junior doctors do." He hoped they also enjoyed a just and fair reward, he said.
Dr Edwin Boorman, the British Medical Association spokesman for junior doctors, retorted that he had never met an executive who had to make life or death decisions.
Dr Boorman said a recent survey showed more than half of junior doctors were working more than the 72 hours maximum they were supposed to. The basic pay started at £12,500 and the best paid earned at most £36,000.
"If he [Sir Iain] finds it relaxing to work flat out with just one or two hours' sleep over a weekend, constantly being aware of patients' health and having to break bad news to people, he has obviously missed his vocation," he said.
Sir Iain, who sits on the CBI committee set up to investigate executive pay, also told the MPs that he held a second job as non-executive vice-chairman of the Royal Bank of Scotland - on a salary of £50,000 a year for one and half days' work a month.
Later Sir Iain sought to make amends, regretting on ITV's News at Ten the way the remark came out. "I have sympathy with them for working such long, hard hours," he said.Reuse content