  We study with lattice techniques the localisation of gauge fields on domain
wall defects in 2+1 dimensions, following a scenario originally proposed by
Dvali and Shifman for 3+1 dimensions, based on confining dynamics in the bulk.
We find that a localised gauge zero-mode does exist, if the domain wall is wide
enough compared with the confinement scale in the bulk. The range of
applicability of the corresponding low-energy effective theory is determined by
the mass gap to the higher modes. For a wide domain wall, this mass gap is set
by ``Kaluza--Klein modes'' as determined by the width. It is pointed out that
in this regime the dynamical energy scales generated by the interactions of the
localised zero-modes are in fact higher than the mass gap. Therefore, at least
in 2+1 dimensions, the zero-modes alone do not form a low-energy effective
gauge theory of a traditional type. Finally, we discuss how the situation is
expected to change in going to 3+1 dimensions.
