It was not Red but the colour Purple which was the stuff made for royalty in ancient times, worn by Kings and aristocrats.
Roman men wore the purple coloured dress with pride, especially during religious ceremonies. Tyrian purple also is known as "royal purple" was produced by species of predatory sea snails was converted by high fliers of Roman society.
Shades of purple
Different shades of purple worn by men in ancient times almost suggested their social status in society.
Reddish purple was worn by the nobility and the plainer version was used by the lower class of society. Colours expressed status in society, Romans mainly followed Greek tradition.
'Justinian the Great'
Byzantine Emperor Justinian-I also was known as Justinian the Great, is shown in Tyrian purple at the Basilica mosaic in Italy.
Justinian-I was the eastern Roman emperor from 527 to 565. His reign was marked by high art and was also known for rewriting of Roman law, the Corpus Juris Civilis.
Queen Elizabeth's reign
Under Queen Elizabeth's reign (1558 to 1603) Sumptuary Laws which regulated colors, fabrics, and clothes which people in England could wear, and naturally Purple was forbidden to be worn by anyone except by the royal family and their relatives.
The current Queen Elizabeth -II also wears purple on several occasions, sometimes on important occasions.
Roman emperor Aurelian
Roman emperor Aurelian famously disallowed his wife to buy a shawl made from purple silk because it literally cost its weight in gold!