  We conduct the first self-consistent numerical simulations of a recently
discovered population of 47 large, faint (ultra-diffuse) galaxies, speculated
to lie in the Coma cluster. With structural properties consistent with very
large low surface brightness systems (i.e. $\mu$(g,0)$<24$ mag arcsec$^{\rm
-2}$, r$_{\rm eff}$ comparable to the Galaxy), the red colour
($\langle$g-r$\rangle$$\sim$0.8) and assumed low metallicity of these objects
compels us to consider a scenario in which these are underdeveloped galaxies
whose early ($z$$\simeq$2) accretion to an overdense environment quenched
further growth. Our simulations demonstrate the efficacy of this scenario, with
respect to available observational constraints, using progenitor galaxy models
derived from scaling relations, and idealised tidal/hydrodynamical models of
the Coma cluster. The apparent ubiquity of these objects in Coma implies they
constitute an important galaxy population, we accordingly discuss their
properties with respect to a $\Lambda$CDM cosmology, classical LSBs, and the
role of baryonic physics in their early formation.
