This camera is the UK version of the No. 4 Eureka. There the Eureka name was already in use by W. Rouch & Co. for a plate camera, so Eastman Kodak had to rename their Eureka.
The Zenith was introduced in October 1899 and discontinued in 1900. Only 1000 were made, starting from serial number 701. The example in this video has number 881. It is a very rare camera.

There is no difference between the Eureka and Zenith, except for the name, which is printed inside the back door, on the focusing scale and on the strap.