For a LC_TIME="en_GB.utf8" locale, nl_langinfo(T_FMT) just returns "%H:%M:%S" directly without the intermediary"%T. So perhaps just grep the return value of T_FMT for any of %H, %k, %R, or %T.
For a LC_TIME= "en_GB. utf8" locale, nl_langinfo(T_FMT) just returns "%H:%M:%S" directly without the intermediary"%T. So perhaps just grep the return value of T_FMT for any of %H, %k, %R, or %T.