Colonel (Col) is a rank of the British Army and Royal Marines, ranking below brigadier, and above lieutenant colonel. British colonels are not usually field commanders; typically they serve as staff officers between field commands at battalion and brigade level. The insignia is two diamond-shaped pips below a crown. The crown has varied in the past with different monarchs; Elizabeth II's reign used St Edward's Crown. The rank is equivalent to captain in the Royal Navy and group captain in the Royal Air Force.

Listed in the table below are the insignia—emblems of authority—of the British Army. Badges for field officers were introduced in 1810 and the insignia was moved to the epaulettes in 1880. On ceremonial or parade uniforms these ranks continue to be worn on the epaulettes, either as cloth slides or as metal clips, although on the modern 'working dress' they are usually worn as a cloth slide on the chest. Although these insignia apply across the British Army there is variation in the precise design and colours used and it can take some time to become familiar with them all.