Queen Elizabeth's secret tunnel outside Windsor Castle exposed in mysterious snaps

Queen Elizabeth made her much-awaited return to the Windsor Castle after spending the summer in Balmoral with Prince Philip. 

As the Queen quietly resumes official affairs at the royal residence, shocking elements about the 900-year-old estate came to light in a series of pictures doing the rounds of late.

Windsor Castle, in addition to being a working palace, was also a fortress, which means there are lots of secret passages and hidden former defences.

One of the secret features of the castle is a hidden escape tunnel which the Queen can use anytime she wants in order to make a quiet exit!

The tunnel is hidden beneath a trapdoor covered by carpet and revealed in detail in a 2011 BBC documentary The Queen's Palaces.

"As if by magic, just lift these and the medieval castle emerges. If you’re a soldier in Windsor Castle under siege you need a way to get out. And this is the secret passage,"  presenter Fiona Bruce says in the documentary.

“This is exactly what it looked like in the 1200s. It’s wide enough to accommodate a whole army of men. You can just imagine them rushing down the stairs, and it leads out onto the street. This is the clever bit - they’d then be able to sneak up on the enemy and attack them from behind," she adds. 

Check out the secret tunnel in pictures below