In a research article published last year we reported red shifting of the charge transfer band of Reichardt's dye in the visible spectrum when the solvent was vibrationally coupled to an optical cavity, indicating a change in the polarity of the solvent. The magnitude of the observed shifts correlated with the alkyl chain length of the alcohol solvents and with their polarizability and solvent-accessible surface area. To confirm that the observed effect was caused by Vibrational Strong Coupling (VSC) we conducted control experiments, known as detuning experiments, under off-resonance conditions in which none of the vibrational bands of interest were coupled to the cavity. These experiments showed no shifts. We interpreted these experiments as evidence that strong coupling is responsible for the observed shifting, and that the change in solvent polarity was due to the impact of VSC on London dispersion forces within the coupled solvent.