Ah, this old chestnut!
Firstly, you'd have to state your definition of high volume. It's no Hiwatt or Fender Twin, for sure. It's all relative, so the answer, as Dave alludes, is: relatively, no.
However, like all JTM45s, it produces 30-35 Watts of clean power (with a nominal THD). Many people would say that a 35W valve amp is quite loud.
It's enough to gig with, in a pub in a 5 piece band, with a clean sound, using a 2x12 cab, at decent volumes, but without searing peoples brains. Is that high volume? Relatively, no. Is it loud enough? Possibly.
Also note that it has more harmonic colouration when nominally clean than many other amps, which is what makes it such a great clean amp, IMO. However some people mean crystal clean. How clean is your clean?
P.S. The original owner of this plays blues, not too dirty and with a Strat, and complained that it was too loud! Hence the master volume. The cab has G12H-30s which are a very efficient speaker, mind.