At least there is some military experience here:
Having military experience is not necessarily a guarantee of being a good Defence Secretary. Malcolm Rifkind had no military experience - but was very popular and competent as DS, principally for energetically advancing and defending the MOD budget in cabinet, but then letting MOD control how they spent it without too much political interference. On the other hand, John Nott was a former Ghurka officer, but was widely ridiculed and disliked as DS.