 The name of the island is derived from Platt of Molesey who used it for growing withers.Boatbuilding began on the island in 1868, when Thomas Tagg, who had been running a business since 1841 on Tagg's Island, about downstream, expanded by building a boatyard and house on the eastern end of Platt's Eyot.A waterworks and electrical works with a charging station were also constructed on the island; the latter was used to power electrically powered pleasure launches and canoes that were built on the island.