 After Lavasani 's body had been recovered , Sir David McNee , Commissioner of the Metropolitan Police , contacted the Home Secretary to request approval to hand control of the operation over to the British Army , under the provisions of Military Aid to the Civil Power . Whitelaw relayed the request to Thatcher , and the prime minister agreed immediately . Thus John Dellow , the ranking police officer at the embassy , signed over control of the operation to Lieutenant Colonel Mike Rose at 19 : 07 , authorising Rose to order an assault at his discretion . Meanwhile , the police negotiators began stalling Oan . They offered concessions in order to distract him and prevent him killing further hostages , buying time for the SAS to make its final preparations for the now @-@ inevitable assault . 
