A couple of other little gems you may or may not know...
1. If awarded the LS&GC and then subsequently commissioned, you are entitled to the clasp (and rosette when wearing the ribbon only) provided you commissioned after 22 years of service as an "OR". If commissioned before that point, no clasp.
2. It is possible to have two LS&GC. Initial LS&GC awarded whilst in one Service, individual then transfers with unbroken service. When elligible for clasp, he can not be awarded a clasp to his original as he is no longer in that Service therefore he gets an LS&GC from his current Service. There are currently two in the AAC in that situation.
Howzat!