A antheral successful his 30s has been arrested connected suspicion of breaking into the grounds of Windsor Castle.
The antheral was spotted by Metropolitan Police officers aft 1pm connected Sunday and "quickly challenged".
He was subsequently arrested connected suspicion of trespass and for possession of Class-A drugs.
The antheral was past passed into the custody of Thames Valley Police.
The constabulary said helium has since been bailed, and an probe is ongoing.
Sky News understands nary members of the Royal Family were successful the castle astatine the time.
The constabulary added that the antheral had not entered the interior grounds of the castle.
It is simply a transgression offence to trespass connected a protected tract designated nether the Serious Organised Crime and Police Act 2005.
Read much connected Sky News:
Madeleine McCann hunt nether mode successful Portugal
Trump's tariffs announcement casts uncertainty implicit UK-US deal
In October past year, another information scare took spot connected the Windsor Castle property erstwhile masked burglars broke successful portion members of the Royal Family were believed to person been dormant nearby, the Sun reported.
Two men reportedly scaled a 6ft fence, and past utilized a stolen motortruck to interruption done a information gross - aft fleeing connected quad bikes.
The King and Queen were not successful residence astatine the time.
Another information incidental took spot connected Christmas Day successful 2021 - involving a antheral climbing a obstruction astatine Windsor Castle, equipped with a crossbow and claiming helium wanted to termination Queen Elizabeth II.
Jaswant Singh Chail was handed a nine-year custodial condemnation for treason, possession of an violative weapon, and making threats to kill.