As a geometrical effect strong lensing is sensitive to the distances between observer, lens and source. These distances are a sensitive probe of cosmological parameters, but it is difficult to disentangle the distances from the unknown lensing mass. Where two background lensed sources feel the same lensing mass a new observable, the cosmological scaling factor, can be inferred that is sensitive to cosmology.
Morphologically simple multiple-source-plane lenses are rare, but extremely powerful probes of dark energy. In this talk I will present the first measurements of cosmological parameters using a galaxy-scale double-source-plane lens (SDSSJ0946+1006 or “The Jackpot”). I will discuss ongoing work in minimizing the systematic uncertainties of the approach and outline how multiple-source-plane lens cosmography can remain a powerful cosmological probe in the LSST/Euclid/SKA era.