The Royal Regiment of Canadian Artillery: Regimental colours (not standards)
 

Found this tidbit of information at The Royal Regiment of Canadian Artillery:

411. The Corps Colour Of The Royal Regiment

1. The corps colour of The Royal Regiment of Canadian Artillery is red. It is a deeper shade than scarlet but lighter than cherry. Blue has traditionally been the colour of an artilleryman’s coat. The reason for this has been lost to historical record but it has been suggested that blue was a preferable colour due to the dirty nature of working with black powder guns, and that cavalry and infantry alone were entitled to wear the royal scarlet being the servants of the sovereign. Artillerymen, being originally the civilian employees of the various officials of the ordnance, did not enjoy this privilege and so adopted the sister colour of blue. This distinction was eventually recognized and perpetuated when clothing regulations were formalized, with blue being generally accepted as belonging to the artillery.

2. The corps colour, red, is not used on full dress or mess dress. The correct colour is the distinguishing colour of the Artillery, which is scarlet. The distinguishing colour is used for facings, cuffs, trouser stripes, busby bags, and similar applications. These applications of scarlet reflect the traditional royal facings on artillery uniforms and have nothing to do with the corps colour.

3. The Artillery uses red over blue on regimental flags, standards, pennants, signs, and wherever else artillery colours are required. The colours are a direct extract from the British Flag and are referred to as Union Jack Red and Blue.