flux inside the source plane (SP) pixels with SNR $\geq3$ and $F^{\rm LP}_{3\sigma}$ the total flux inside the corresponding lensed pixels. Similarly, $r_{\rm eff}$ are measured from the reconstructed source area recalling that $A^{\rm SP} = \pi r_{\rm eff}^2$.

The retrieved magnification are respectively 7.80 and 17.39 for the HST/WFC3 and ALMA observations. The first value is higher than (but consistent within $2.5\sigma$ with) the value $μ_{tot}\sim6.3$ reported in Dye et al. (2014, but the lens was modelled with a Singular Power Law Ellipsoid and resulted to be more spherical than what we find), the second is almost twice the value of $\mu_{880}$ reported in Bussmann et al. (2013), even though it is worth noticing that in that case the lens modeling method was a fully parametric one, with the reconstructed source modeled with a Sersic profile. Anyway, the high value of $\mu_{1.3}$ is expected since the reconstructed source is compact and peaks close to the lens caustic. Source properties are reported in Table \[table:sourceprop\].

The observed lens planes and reconstructed source planes are superimposed in Fig. \[fig:composite\_results\]. From a visual inspection of the lensing morphology, there is a clear presence of a displacement between the two data sets. This 