Watch animal rights activists transform King Charles' face into Wallace, from Wallace and Gromit

Ah, this refers to a different portrait.

The portrait of the King that will hang in public buildings such as courts and government offices has been unveiled.
Taken in Windsor Castle, it is a very traditional formal portrait of the King in an Admiral of the Fleet uniform, with medals and honours on display.
Public bodies such as schools and councils can request a free A3-size, oak-framed copy of the photograph.

But obscuring that sort of portrait wouldn’t have the effect that these nitwits woould like.