unique properties have been attributed to their special location at the cluster centres [@Hausman1978]. These properties may also suggest that the formation of BCGs are different from that of other ETGs [e.g. @Burke2000; @Stott2008; @Stott2010].

Due to the privileged positions of BCGs at the centres of their host clusters, these massive galaxies are expected to experience multiple mergers during their lifetime, making them ideal probes with which to study galaxy formation. Observational evidence, for example tidal tails and distorted isophotes, indicates that some BCGs are experiencing mergers [e.g. @Bernardi2007; @Lauer2007; @2007; @McIntosh2008; @Liu2009; @Liu2015; @Rasmussen2010; @Brough2011], but it is not clear to what extent their stellar mass is being built up by mergers and at what rate.

There is currently no consensus in the literature regarding the stellar mass evolution of BCGs between $z=1$ and the present day. Observational studies have found that these massive galaxies changed their mass by factors that range between one [equivalent to no growth; e.g. @Aragon-Salamanca1998; @Whiley2008; @Collins2009; @Stott2010; @Oliva-Altamirano2014] and $1.4 \pm 0.2$ [@Lin2013] or $1.8 \pm 0.3$ [@Lidman2012] since $z \lesssim 1$.

Predictions from numerical simulations and semi-analytical models (SAMs) suggest that BCGs form in two ‘phases’. They suggest that star formation dominates 