  Geometric frustration is an approach to the glass transition based upon the
consideration of locally favoured structures (LFS), which are geometric motifs
which minimise the local free energy. Geometric frustration proposes that a
transition to a crystalline state is frustrated because these LFS do not tile
space. However, this concept is based on icosahedra which are not always the
LFS for a given system. The LFS of the popular Kob-Andersen (KA) model
glassformer is the bicapped square antiprism, which does tile space. Such an
LFS-crystal is indeed realised in the $\mathrm{Al_{2}Cu}$ structure, which is
predicted to be a low energy state for the KA model with a 2:1 composition. We
therefore hypothesise that upon changing the composition in the KA model
towards 2:1, geometric frustration may be progressively relieved, leading to
larger and larger domains of LFS which would ultimately correspond to the
$\mathrm{Al_{2}Cu}$ crystal. Remarkably, rather than an increase, upon changing
composition we find a small decrease in the LFS population, and the system
remains impervious to nucleation of LFS crystals. We suggest that this may be
related to the composition of the LFS, as only a limited subset are compatible
with the crystal. We further demonstrate that the $\mathrm{Al_{2}Cu}$ crystal
will grow from a seed in the KA model with 2:1 composition and identify the
melting temperature to be 0.447(2).
