Full Idea
Faradays' measurements predicted the speed of electro-magnetic waves, which happened to be the speed of light, so Maxwell made an inspired leap: light is an electromagnetic wave!
Gist of Idea
Electro-magnetic waves travel at light speed - so light is electromagnetism!
Source
Frank Close (Theories of Everything [2017], 3 'Light!')
Book Reference
Close,Frank: 'Theories of Everything' [Profile Books 2017], p.39
A Reaction
Put that way, it doesn't sound like an 'inspired' leap, because travelling at exactly the same speed seems a pretty good indication that they are the same sort of thing. (But I'm not denying that Maxwell was a special guy!)