Special anti-truck-ram barriers are installed at the four roads leading into estate.
New anti-terror measures have been put in place around the Queen's Sandringham estate for the first time as several high-profile royals stay there for the festive season.
Special anti-truck-ram barriers have now been built at the four roads which lead to the Royal residence in Norfolk.
The three-foot-high modular barriers can erected in seconds by police officers in the event of a terror attack involving a heavy goods vehicle.
They have been designed by Belgium company Pitagone and can stop trucks weighing up to 7.5 tons travelling at up to 30mph.
The special barriers are fully adjustable and can be used on all types of terrain and, because of their modular design, they can be built very quickly.
The barriers were all on stand-by today as the Queen and other members of the Royal family attended the weekly Sunday service at Mary Magdalene Church.