Yeah, JCM900s are clearly visible onstage in (for example) the Stage Fright video, though the editing is too fast for me to be able to see much of how they might be configured!

The JVM410s are pictured in a recent post on Paul Marshall's blog, but not clearly enough that I can see them there either.

I know Phil has used various amps over the years -- and doubtless still does in the studio -- though is live rig seems to have been mostly Marshalls of late. There's an amusing interview with Lemmy and Phil from just after Sacrifice here in which Lemmy slags off JCM 800s: "They're garbage"! "We're gonna try and get him [Phil] an old stack," Lemmy pronounces. I guess Phil's still happy with newer ones, though.