This paper presents the results of some dedicated experiments performed on Joint European Torus (JET), and related simulations, that clearly demonstrate the existence in JET of a neutral point (NP) for density limit disruptions. It has been observed that a plasma, specially designed to be set at different vertical equilibrium position without altering the shape, moves upwards (downwards) when the disruption is triggered with the plasma below (above) the NP. The CREATE_L linearised plasma response model applied to such configurations is able to predict and explain the most significant qualitative features of the experiment.