Yes, it is odd, especially as the 1871 Every St entry has an 1857 James being an apprentice joiner. The 1881 description of cab driver from Gloucestershire would fit better with the 1835 James, who in 1871 was a groom from Gloucestershire - I'm thinking that a groom, being someone who cared for horses, might at some point become the driver of a horse & carriage. Unless he took over from his father for a time to help out, or something?

In the absence of anything in the IGI I can't think of anything better than trawling through the local parish registers for Port Erin around that date, or for Everton, although someone more experienced or expert than me might come up with something better. Sorry can't be more help - just have easy access to the censuses.