Class 4700 are a series of medium power electric locomotives built by Siemens for Comboios de Portugal, the state owned railway company of Portugal. They were built to replace the CP Class 2550 locomotives dating from the early 1960s. Siemens were the natural choice for the original order for 15 machines, placed in 2006, as they built the older Class 5600 locomotives in the 1990s. An option for 10 further locomotives was provided for, and this was taken up in 2007, with delivery following on from the original batch.