  The majority of Galactic globular clusters (GCs) contain multiple stellar
populations displaying specific chemical abundance variations. In particular,
GCs generally contain a `primordial' population with abundances similar to
field stars, along with an `enriched' population exhibiting light element
anomalies. In this paper we present a homogeneous and wide-view analysis of
multiple stellar populations in 28 Galactic GCs. By using a combination of HST
photometry together with wide-field, ground-based photometry we are able to
analyse between 84% and 99% of all stars in each cluster. For each GC, we
classify stars into separate sub-populations using the well-established
$C_{\rm{UBI}}$ colour index, and investigate the spatial distributions of these
populations. Our results show that dynamically young GCs can contain either
centrally concentrated enriched or primordial populations, or no centrally
concentrated population. Dynamically old GCs show fully mixed populations as
expected. The existence of clusters born with centrally concentrated primordial
(and homogeneously mixed) populations exacerbates the mass-budget problem
facing many cluster formation scenarios. The diversity in these results also
highlights the need for additional theories that can account for the wide
variety of initial conditions that we find. We finally investigate the enriched
star fraction as a function of different global parameters in our GC sample,
using also data for young and low-mass clusters from the Small- and Large
Magellanic Clouds and confirm earlier results that the enriched star fraction
strongly correlates with the initial mass of a cluster.
