hi carolyn
the short answer is i don,t know wether he would be demoted a rank if he changed regt,s you need Ken,s expertise for that answer as some of these upper nco ranks don,t appear to be straight forward promotions , can,t think how else to explain it what with warrant officers with different classes colour sgts rsm,s qms,s i,ve never understood the direct line to the top of the pile

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best wishes
trevor