additional shear strength to the flange 105 reinforcement layers 144 may be included in any of the modular structural composite beam configurations described herein fig5 shows a further alternative configuration of an upper section of a modular structural composite beam 200 elongate elements 40 and the skin member 260 comprises only a single skin element 220 which partially surrounds elongate elements 40 a 40 b and 40 c of the array it will be appreciated that any number of elongate elements 40 140 may be included in the array which forms the body 42 142 242 and any number of different fibre reinforced plastic materials in any desired arrangement may be selected for the elongate elements in this way the mechanical properties of the flange 5 105 205 may be varied as desired referring again to fig2 if the width of the body 42 stays the same three elongate elements wide but the depth changes for example two elongate elements deep the same skin elements 20 30 can be used since the difference in depth is accommodated by the fact that the second skin element 30 fits into the first skin element 20 until it reaches the body 42 if desired the sides 22 of the first skin element 20 may be trimmed to remove the overlap with the projections 32 of the second skin element 30 alternatively a greater depth body 42.