The Buckingham was the separate head and cab version of the Vox Viscount 2x12 combo amp. You can read about the development of the Viscount amplifier by clicking here.

In 1965, after Thomas Organ in the US inked their distribution deal with Vox in the UK, Thomas published their first Vox product catalog. It featured the British Vox tube amps with new "easy to remember" names for the American market. The British Vox AC-30SRT (Super Reverb Twin) was renamed the "Vox Buckingham." See this entry from the 1965 US Vox catalog above.

Very few Vox AC-30SRT tube amps were imported by Thomas Organ from Vox in the UK. Instead, Thomas was busy developing their own solid state versions of the Buckingham and Viscount under the direction of their brilliant engineer, Sava Jacobson. The Thomas versions of these amps would be manufactured in California.

The solid state Buckingham and Viscount amplifiers are unique in that they feature a 35 watt RMS output amplifier that uses a pair of matched germanium power transistors. I believe that Vox engineer Sava Jacobson chose germanium transistors for the solid state US versions of the AC-30 because these transistors had a more "tube like" tone. Unlike the Buckingham, the higher powered Super Beatle, Royal Guardsman and Westminster had silicon power transistors in their output stage. I suspect that germanium transistors were not used in these amps because silicon output transistors were more dependable in higher powered amps.

It should be noted that the beloved trapezoidal shape used for Vox amp head cabinets originated with the AC-30SRT. Thomas Organ copied the cabinet shape for their Buckingham, and later kept the design for the Westminster, Royal Guardsman and the Super Beatle amp heads.