Labour's deputy leader hoped to set the political agenda with a plan to overhaul rules on standards in public life. But she was only told about Sir Keir's plans minutes before she went on stage - hours after journalists were tipped off.
Early yesterday, Ms Rayner told broadcasters she was not aware of any reshuffle, adding: "I reckon Keir would tell me first."
But she admitted after her speech that she had been kept in the dark.
Ms Rayner said: "I don't know the details of the reshuffle or the timing of it." Her spokesman added: "She was not consulted on the reshuffle."
Tensions between the pair erupted earlier this year when he sacked her as party chairwoman and campaign coordinator after Labour received a drubbing in local elections.
The resulting backlash forced the leader to give her a raft of new responsibilities.
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Yesterday's shadow cabinet refresh was viewed as a move by Sir Keir to bolster his floundering leadership.
Yvette Cooper was appointed to the high-profile role of shadow home secretary. She replaced Nick Thomas-Symonds, who was blamed by senior figures for failing to make an impact against Home
Secretary Priti Patel over the Channel migrant crisis.
Lisa Nandy, a contender in the last leadership election, was replaced by David Lammy as shadow foreign secretary. She will now take on Michael Gove as shadow levelling-up secretary.
Ex-leader Ed Miliband was stripped of responsibility for business. Instead he will oversee climate change and "net zero" policy.