  We present a framework that explains the commonly observed variation in light
element abundances in globular clusters. If globular clusters form in the
centres of dwarf galaxies, they will be pumped onto larger orbits as star
formation progresses. The potential well will only retain the moderate velocity
AGB ejecta, the expected source of enrichment, but not supernova ejecta. There
is no need to increase the initial cluster mass, a requirement of
self-enrichment scenarios, as all the stars within the dwarf can contribute. As
the clusters move through the dwarf centre they sweep up a mix of AGB ejecta
and in-falling pristine gas to form a second generation of stars. The specific
mix will vary in time and is thus able to explain the spread in second
generation abundances observed in different clusters. The globular clusters
will survive to the present day or be stripped as part of the hierarchical
merging process of larger galaxies. We illustrate how this process may operate
using a high-resolution simulation of a dwarf galaxy at high redshift.
