According to the Royal Household:
The Queen…has presented a Guidon to The Royal Lancers during a ceremony in St George’s Hall, Windsor Castle.
During the traditional ceremony at Windsor Castle Her Majesty touched the new Guidon, and presented it to the Regiment.
A Guidon is a heraldic banner carried by cavalry regiments. They were traditionally carried into battle as distinguishing symbols and rallying points for fighting units.
The Royal Lancers are 12 Armoured Infantry Brigade’s Armoured Cavalry Regiment based in Catterick, North Yorkshire. They have extensive operational experience, having been the last regiment to operate the Combat Vehicle Reconnaissance in Afghanistan.