The question of the existence of preons can be asked in any supergravity theory, except that the amount of supersymmetry preserved by a preon depends on the nature of the spinors. For example, is theory with real spinors and n supercharges preons are defined as backgrounds which preserve a fraction ν = (n-1)/n of the supersymmetry. If the spinors are complex and the Killing spinor equations are complex linear, so that the real supercharges are real and imaginary parts of Killing spinors, then this number is always even, whence preons ought to preserve a fraction ν = (n-2)/n of the supersymmetry. Similarly if the Killing spinors are quaternionic, then the preonic fraction is ν = (n-4)/n.
Jai Grover, Jan Gutowski and Wafic Sabra looked at the problem of the existence of preons in four- and five-dimensional gauged supergravities, where the preonic fraction is ν = 3/4 and concluded that any such background is locally maximally supersymmetric; that is, it is a discrete quotient of the relevant anti de Sitter space. So far, things seemed to be as in the case of eleven-dimensional supergravity and it was natural to think that a similar analysis to the one in my paper with Sunil might prove the non-existence of preons also in these theories. However preserving a fraction 3/4 is not as strong as preserving 31/32 and ruling out such quotients would have involved more work.
The perhaps surprising result was that among the AdS quotients that Joan and I studied there were some which already preserved ν = 3/4 of the supersymmetry in AdS4 or AdS5. Such quotients turn out to be smooth and hence Jan, Wafic and I wrote a short paper expliciting these solutions including, for the sceptics, an explicit construction of the Killing spinors in such quotients.
To my knowledge this is the first case where a fraction of the supersymmetry ruled out by the local analysis of the Killing spinor equations has been resurrected by global effects, namely the topology of the underlying spacetime. Let this be a lesson to us all!