The Marquis of Bute who was really responsible for changing and developing Cardiff into a major city.
When coal became king in the late 18th century, the Butes built the Cardiff canal to Merthyr to aid industrialisation. But the area's potential and prosperity wasn't fully realised until John, the 2nd Marquis - son of Lord Mountstuart - commissioned the first of the great docks on the Cardiff waterfront.
The Bute Dock opened in 1839, paving the way for Cardiff to become the biggest and most prosperous coal port in the world. [BBC website]
If you ever fancy a read of the history of Cardiff, albeit a fictional story but based on fact, try "River out of Eden" by Jack Jones