I was looking at the time of the challenge and noticed it was UTC. In the most basic sense this is synonymous with GMT to me. Which means, if my logic is correct, the British discovered time. Such a fine discovery. For this alone, they can name the channel anything they want.
Mancha in Spanish has many meanings. Spot, stain, mark, blotch, blemish-- "X marks the spot" etc.
Have fun with that one....