By Agence France-Presse
In a rare honour which requires the Queen's consent, Keith Palmer's coffin was brought to a chapel within the Westminster parliament under police escort where it will lie overnight ahead of his funeral on Monday.
Others who have previously been granted the honour include former prime minister Margaret Thatcher.
Thousands of police officers from forces across the UK are expected to attend the murdered officer's funeral at London's Southwark Cathedral.
Palmer, 48, was fatally stabbed as he stood guard in front of parliament last month by Khalid Masood after the 52 year-old convert to Islam drove into pedestrians at high speed near parliament, killing four other people.
Masood was shot dead by an armed officer.