Well, he didn't. Here's what Andrew Grice said about it, in full. Rather more than Brown said, in fact:
Gordon Brown angered MPs in all parties today by rejecting calls for an immediate inquiry into the causes, conduct and cost of the Iraq war and its aftermath. Reporting to the Commons on his flying visit to Iraq yesterday, the PM insisted it was not the right time to set up the inquiry he has promised while 4,100 British troops remain in the country.
Opposition parties smell a rat. They believe Brown's game is to stall the start of an investigation for as long as possible, so that it could not report before the next general election. They even expect Brown to hide behind the presence of up to 400 servicemen in Iraq after the bulk return home by next July.
Brown aides say he will make as decision the timing of an inquiry next summer. If he tries to use the remaining personnel as an excuse, he may have a problem. David Miliband, the Foreign Secretary, told MPs last week: "We are not going to hide behind the idea that the last troop must have come home." We shall see.