I have several dictionaries of phrase origins and meanings, the oldest of which is by Ebenezer Cobham Brewer;  the edition I own was published in about 1896.

Here are a few  “Red”  definitions

Red Tincture was a preparation that alchemists thought would convert any baser metal into gold. It is sometimes called the Philosopher’s Stone, the Great Elixir or the Great Magisterium.

Red-shanks was used to describe a Highlander and came from the boots made of undressed deer hide that Highlanders once wore  with the red hair still on the outside.

Red-lattice  at the doors and windows of an English alehouse used to signify that it was properly licensed to sell alcohol;  it is probably the reason why many old public houses are called “The Chequers.”

Red-tape originates from the custom of lawyers and government officials of tying their bundles of papers together with red tape; it has been in use since the 18th Century and now generally refers to bureaucratic delay.  In David Cameron’s first speech as PM he said that he would help small firms by cutting red tape;  well,  he hasn’t helped ours and we are being strangled by it. I do not think I shall live to see any Government reducing Red Tape!

Red-breasts (or Robin redbreasts) was the slang name for The Bow Street Runners who were the first professional policemen in London and wore bright scarlet waistcoats.

Can you add any more?