In the past decade, large amounts of information has been collected in order to understand the broad characteristics of the galaxies in the early Universe. However, to reach a full understanding of thecomposition of various types of high redshift galaxies, we need to understand the diversity of individual galaxies in greater details. Strong gravitational lensing magnifications provided by a chance alignment of a large mass concentration towards background higher redshift galaxies allow us to probe the physical characteristics of fainter and more distant galaxies to a greater level of detail than otherwise possible to reach with current observational facilities. This application focuses on the use of data from a new sensitive spectrograph, X-shooter at the Very Large Telescope, for observations of gravitationally lensed galaxies which are recently discovered, or will be discovered in a Hubble Space Telescope Multi-Cycle Treasury Programme on distant massive galaxy clusters.I will determine the redshifts of the lensed galaxies, derive models of the mass distribution in the lensing clusters, and find the magnification factors produced by the system. By combining the multi band HST images with ground based spectra I will use both unique data sets to obtain unprecedented details necessary for the characterisation of the nature of high redshift galaxies. I will determine the rangeand diversity of physical parameters pertaining to the nature of the lensed galaxies such as metallicities, dynamics, and star formation histories, which are all relevant for our understanding of the evolutionary sequence of galaxies throughout the Universe. Thisproject will give us a glimpse into the potential discoveries which will be possible to reach for unlensed high redshift galaxies with the next generation of telescopes.