For what it is worth, even the F-111 only had limiting Skin Temp that generally kicked in above approx M2.2, and I have occasionally seen it NOT to be a factor until M2.3+.
Presume Bucc - For all its glory cannot go there, and the Tornado lacks enough (internal) fuel to sustain that number for any time sufficient to be a factor, and B4 you raise the Tornado's fuel - If it carreid External Tannks to go the distance, its Fuel Tank Drag = No-Go to much above the Mach 1 number (Ignoring of course the Release to Servie Lims
).
SR-71 on the other hand......
