I realized after I posted that I should have clarified that I categorize all of the Rivendell-branded frames,i.e. the ones without another name, as “Custom”. That includes all the early Waterford-built Road, Long-Low, All-Rounder, and ATB frames.
Waterford considered every Rivendell frame to be a custom build, which was one of the reasons we created Heron.
In this case, based on the lugs and the parts, I wouldn’t be surprised if this is an earlier frame with a repaint. I didn’t spend a lot of time examining the details, though.