There's a more detailed PDF of the Protium project here. They don't claim it's a 'first', which is just as well, because it isn't.
An article from 7 years ago, "Are fuel cells the new rock n' roll?", describes Zetek, a company that set out to prove that you could build boats powered that way.
The first fuel-cell canal boat was Pangea (pictured left), built by Reading Marine in 2001-2 and launched using Zetek's systems. Unfortunately Zetek went bust shortly afterwards, apparently losing funding in the wake of 9/11.
While Pangea worked, it obviously was an impractical concept boat rather than the first in a new generation, because I heard it was later converted to a conventional diesel boat. Or perhaps into a diesel-electric drive. Whatever, Pangea turned out to be a one-off.
Five years later the proof-0f-concept Ross Barlow appears to include several enhancements. However, its trumpeted 'green hydrogen' seems to me simply to be hydrogen generated by wind turbines. I wonder how many wind turbines you'll need to power a fuel-cell narrowboat? And how many to drive all 30,000 of Britain's canal craft?