The blue/white jasper ground is typical and is very similar to the butterfly weight illustrated in Robert Halls "Scottish" book p126. Nice complex canes to the interior of each wing. Definitely the masters work...
I find Pauls butterflies superb technical creations - Johns work can be very good indeed but can be a tad inconsistent. WM follows in his masters footsteps - his butterflies are generally a slightly tweaked design/construction - usually more lampwork, and less millefiori - if that makes sense??
I'm surprised no one mentioned Peter Holmes - his butterflies are fabulous - or Peter McDougal another superb technician.