24a Quarries (9) ?T?N?????
26d Henri's hobby (5,5) ???S? T?M?S (times?)
5d Advocates of the return to Italy of all Italian-speaking districts subject to others' control (12) I?R?D?E?I???
8d The condition of being in a particular place (6) U?I?T? Is this UBIATE?
Thank you all very much. By the time I submitted my own answer there were the answers from you all. Fantastic - now I'll concentrate on The Jubilee Pageant.