Police are carrying out specialist searches as the preparations for the funeral of the Duke of Edinburgh continue.
Thames Valley Police said officers were examining street furniture including phone boxes, post boxes, drains and bins as part of the operation.
Patrols were also being carried out in Windsor town centre, the Long Walk and Home Park.
Thames Valley Police said it has put a range of visible and covert security measures in place for Saturday, when the duke is to be honoured with a ceremonial royal funeral at St George’s Chapel, in the grounds of Windsor Castle.
These include automated number plate checks, use of CCTV and of barriers to prevent attacks using vehicles, as well as armed and mounted officers being on patrol.
Police have asked the public not to gather by royal residences, to avoid meeting in large groups, to minimise travel and to make a donation to charity instead of laying floral tributes.
Reiterating the requests made by the Royal Household and the Government, the force also pointed mourners towards an online book of condolence to pay their respects.