  The flux density from undetected sources in the observing beam of a telescope
produces source confusion noise in the resulting maps of the sky, and thus
limits sensitivity. In a recent paper we discussed this effect in the
millimetre/submillimetre waveband, using a simple model of galaxy evolution
that could account for the gravitationally lensed images of distant dusty
galaxies newly discovered in the fields of clusters of galaxies. New models
explain all the available mm, submm and far-infrared data. The associated
predictions of source confusion noise are presented here. The new and old
estimates agree to within a factor of two on angular scales between about 0.3
and 50 arcmin, and are most similar on angular scales of about 1 arcmin. The
new estimates are greater/less than the old ones on larger/smaller angular
scales.
