King Edward I of England appointed the first English Admiral in 1297 when he named William de Leyburn “Admiral of the sea of the King of England”. The rank of Admiral should not be confused with the office of Admiral of England or Lord High Admiral, which was an office held by the person with overall responsibility for the Navy.
The Royal Navy has had Vice and Rear Admirals since at least the 16th century. When in command of the fleet, the Admiral would either be in the lead or the middle portion of the fleet. When the Admiral commanded from the middle portion of the fleet his deputy, the Vice Admiral, would be in the leading portion or van. Below him was another admiral at the rear of the fleet, called Rear Admiral.
In Elizabethan times the fleet grew large enough to be organized into Squadrons. The admiral’s squadron wore a red ensign, the vice admiral’s white, and the rear admiral’s blue. As the squadrons grew, each was eventually commanded by an Admiral (with Vice Admirals and Rear Admirals commanding sections) and the official titles became Admiral of the White, et cetera.
The squadrons ranked in order Red, White, and Blue, with admirals ranked according to their squadron:
Admiral of the Fleet Admiral of the Red Admiral of the White Admiral of the Blue Vice Admiral of the Red Vice Admiral of the White Vice Admiral of the Blue Rear Admiral of the Red Rear Admiral of the White Rear Admiral of the Blue Promotion up the ladder was in accordance with seniority in the rank of Post-Captain, and rank was held for life, so the only way to get promoted was for the person above you on the list to die or resign. Another way was to promote unsuccessful captains to the rank of admiral without distinction of squadron (a practice known as yellowing—the Captain so raised became known as a yellow admiral).
In the 18th century, the original nine ranks began to be filled by more than one person per rank. The British Navy also maintained a positional rank known as Port Admiral. A Port Admiral was typically a veteran Captain who served as the shore commander of a British Naval Port and was in charge of supplying, refitting, and maintaining the ships docked at harbour. The most powerful Port Admiral position was the Port Admiral of Portsmouth, considered the leading harbour of the Royal Navy.