This is a very nice sailor suit for a small child, probably a toddler. This suit comprises three parts, the shirt, shorts and undershirt or dickie, which is very typical of a boys sailor suit. It is complete with embroidered label of the manufacturer 'Naval Outfitter Frank Williams The Arcade Portsmouth'.
The definition of a sailor suit is: a blouse with a square (often detachable) collar, worn with long or short trousers or a skirt or kilted skirt. It comes in a variety of colour combinations, all blue, blue and white, red and white, or all white. Other names for the sailor suit include Jack tar suit and the man-o'-war suit. Rowe, one of the leading manufacturers of sailor suits, also offered correct accessories in The Royal Navy of England and the Story of the Sailor Suit (ca. 1900) including lanyard and Bo'swain's pipe (whistle), the 'regulation Senet Hat', and the sleeve badges of various naval ranks.
The first sailor suit for a child is generally acknowledged to be that made for Queen Victoria's eldest son, Prince Albert Edward. to wear on a royal visit to Ireland in 1846. The fashion took a while to become established, but turned into a classic of childrenswear, and was still in use (although tending to be for best) in the 1920s. It survives as a choice for pageboys at weddings.