the british rail class 375 electrostar electric multiple unit train was built by bombardier transportation (previously adtranz) at their derby works, from 1999 to 2005. the electrostar family, which also includes classes 357, 376, 377, 378, 379 and 387, is the most numerous type of emu introduced since the privatisation of british rail. the trains are operated by southeastern, along with their class 377 fleet, on regional and outer suburban services.