Gravitational lensing provides a powerful probe of the global mass properties of galaxies, which are best tested using observations at extremely high angular resolution. In addition, through detailed observations of the lensed images,
it is possible to place tight constraints on the nature of dark matter through measuring the abundance and properties of low mass haloes in the Universe via their subtle gravitational lensing signal. Here, we first present new observations with the VLA and
HSA to better understand the source of so-called flux-ratio anomalies in four image gravitational lenses, which historically provided the first constraints on CDM using lensing studies. Next, we will present the analysis of the mass properties of five massive
elliptical galaxies at intermediate redshifts, by combining gravitational lensing and the sensitivity and resolving power of the Atacama Large Millimetre Array (ALMA) and global Very Long Baseline Interferometry (radio VLBI). Using imaging at 25 to a few milli-arcsecond
resolution, we find that complex mass models with angular structure are strongly favoured by the data. In addition, such observations are sensitive to small-scale structure either in the lens or along the line-of-sight to the background source. From such an
analysis of the data from global VLBI observations, we detect of a low mass (million solar mass) dark object, whose properties are inconsistent with a dark matter halo from either cold or warm dark matter models, but may be in agreement with more exotic models,
like self-interacting dark matter. Finally, we present a brief overview of future studies using the SKA and a likely African VLBI facility.
