London & North Western Railway 2-2-2 No. 3020 Cornwall is a preserved steam locomotive. She was built at Crewe in 1847. She was originally a 4-2-2 in 1847, but was extensively rebuilt, and converted to a 2-2-2 in 1858.

As completed in 1847, and first numbered 173, Cornwall was a 4-2-2 with 8 ft 6 in drivers, paired leading wheels of 3 ft 6 in, single trailing wheels of 4 ft and an overall wheelbase of 16 ft 6 in. It was exhibited at the Great Exhibition of 1851 in this condition.

In 1858, Ramsbottom redesigned Cornwall almost completely. Little survived unchanged, other than the outside frames and the centres of the drivers. The boiler was now moved entirely above the driving axle, without any notches, channels or tubes, to what would now be regarded as conventional practice. New cylinders and valve gear were provided. Wheel arrangement was now 2-2-2, shortening the wheelbase still further. Ramsbottom also included his newly designed tamper-proof safety valves. Another minor rebuild in the 1870s provided a typically LNWR style of cab, with a short roof and semi-open sides. She was given her current number of 3020, in June 1886.

Cornwall was a famously successful high-speed passenger express engine of its period. On final retirement, Cornwall was deliberately preserved, one of the first locomotives to be so treated.