That’s his wools (white horsehair), hence the phrase ‘pull the wool over his eyes’. They come from the reign of Charles II and have a symbolic purpose that shows both anonymity and authority.

I think only judges at Crown Courts would wear them. You wouldn’t see them in magistrates courts or county courts.

They also used to be used in the 17th century to hide symptoms of diseases such as lice, hair loss, scabs etc.