Weighted mean M/L_V of the DF2 GCs for distances of 16.2 Mpc (black) and 21.7 Mpc (orange) compared to expectations from the MILES models (Vazdekis et al. 2010) for a bimodal IMF with a range of slopes (Vazdekis et al. 1996). Γ = 1.3 corresponds to a Kroupa IMF (Kroupa 2001). A distance of 16.2 Mpc is consistent with the models for 10 Gyr, in agreement with the DF2 GC ages from MUSE data found in Paper II. A distance of 21.7 Mpc suggests a lower M/L_V which cannot be reproduced for old ages with this parametrisation.