The London and North Western Railway (LNWR) "Precursor" Class was a type of 4-4-0 ("Atlantic") steam locomotive designed by the company's Chief Mechanical Engineer, George Whale. Introduced in 1904, it should not be confused with the LNWR 2-4-0 "Precursor" Class of 1874 designed by Francis Webb, the last example of which was scrapped in 1895. In 1906, a 4-4-2T ("American") tank variant of Webb's engine, the "Precursor Tank" Class, also entered service.