Is there any political screening within the British army? I mean for regular army, not any "sensitive" roles?
If so, what form does it take?
Until relatively recently, a serving soldier could not be a member of any political party, and being a member of a group which is known to support actions or beliefs contrary to Army Values and Standards (for example, a far-right group which supports racism) or having had prior membership of one is a bar to joining the army in most circumstances. There's no political screening for special forces, I can tell you that now, and the same holds for Close Protection of VIPs, including Government ministers. We're all security cleared and vetted, and that coupled with the oath of alleigance is deemed sufficient.