London and North Western Railway (LNWR) 2-2-2 No. 3020 Cornwall is a preserved steam locomotive. She was built as a 4-2-2 at Crewe Works in 1847, but was extensively rebuilt and converted into her current form in 1858.

Under the Whyte notation for the classification of steam locomotives, 2-2-2 represents the wheel arrangement of two leading wheels on one axle, two powered driving wheels on one axle, and two trailing wheels on one axle. The wheel arrangement both provided more stability and enabled a larger firebox than the earlier 0-2-2 and 2-2-0 types. This wheel arrangement is sometimes described as a Single, although this name could be used to describe any kind of locomotive with a single pair of driving wheels.