The mechanical properties of aligned fibres and monofilaments of random copolyesters of 4-hydroxybenzoic acid (HBA) and 2-hydroxy-6-naphthoic acid (HNA) with and without the inclusion of a trifunctional branching monomer have been investigated using both macroscopic and X-ray techniques. Results for unbranched samples are in line with previous work while including the branching monomer reduces both the shear and tensile moduli as measured macroscopically. Annealing the samples increases the moduli. On the scale observed by X-ray diffraction the inclusion of branching has little effect whereas annealing increases the sinuosity of the chains and hence reduces the apparent chain modulus determined by X-ray measurements on samples under stress.