According to Wikipedia, the group name Mungo Jerry “was inspired by the poem Mungojerrie and Rumpelteazer, from T. S. Eliot’s Old Possum’s Book of Practical Cats.” If you go to the Mungo Jerry website, you’ll read that “Ray Dorset is…Mungo Jerry…is Ray Dorset,” the fellow on the left in the photo. And looking at the list of all of the former members of the British group of the 1970s, that would be about correct.
The big hit was In the Summertime, which debuted on the charts on July 11, 1970, and went to #3. Here’s one video and here’s another.