A braided composite spar or preform for a braided composite spar with a plurality of tubular plies of braided fibres. Each ply has a first set of fibres which wind in a clockwise direction in a first series of turns with a pitch between each adjacent pair of turns, and a second set of fibres which wind in an anti-clockwise direction in a second series of turns with a pitch between each adjacent pair of turns. The first and second sets of fibres in each ply are intertwined to form a braided structure. The spar or preform extends lengthwise from a root to a tip and has a tapered portion which tapers inwardly towards the tip. Each ply has a circumference in the tapered portion which reduces as it tapers inwardly. For at least one of the plies the pitches of the first and second sets of fibres increase continuously as the ply tapers inwardly in the tapered portion. The spar or preform can be used to provide a tubular main spar for a winglet. The winglet also has a front spar with a front spar web, an upper front spar cap, and a lower front spar cap. An upper skin of the winglet is joined to the braided spar and the upper front spar cap. A lower skin of the winglet is joined to the braided spar and the lower front spar cap.