Manufacture of wind turbine blades

A method of making a wind turbine blade component comprising an outer shell having a laminate structure, the method comprising:

• providing a blade mould defining a shape of at least part of the outer shell of the blade, the mould extending in a spanwise direction between a root end and a tip end, and extending in a chordwise direction between a leading edge and a trailing edge;
• providing a plurality of dry plies comprising dry structural fibrous material;
• providing a plurality of prepreg plies comprising structural fibrous material impregnated with resin;
• arranging the plurality of dry plies and the plurality of prepreg plies in the mould to form a plurality of layers of the laminate structure of the outer shell of the blade, the dry plies being interleaved with the prepreg plies to form a hybrid shell structure in which the plies are arranged in a staggered relationship such that corresponding edges of the dry plies are offset from one another in the spanwise direction of the mould and/or corresponding edges of the prepreg plies are offset from one another in the spanwise direction of the mould;
• and
• arranging a spar cap in the mould such that a first end of the spar cap is arranged on top of or between one or more plies of the hybrid shell structure,
• wherein the first end of the spar cap is spaced from the root end of the mould, and the hybrid shell structure extends in a spanwise direction between the root end of the mould and the first end of the spar cap.