Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The Type 42 or Sheffield class, are guided missile destroyers used by the Royal Navy and the Argentine Navy. The class was designed in the late 1960s to provide fleet area air-defence. In total fourteen vessels were constructed in three batches, five of which remain in service. In addition, two ships were also built to the same specifications as the Batch 1 vessels for the Argentine Navy, one of which remains in service. The ships, along with the Type 23 frigates, today help to form the backbone of the Royal Navy surface fleet, although their place is being taken by the Type 45 destroyers.