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That makes sense thanks. I'll look out for those in future.

Finished, but must have made a mistake somewhere because can't find the team leader! Any hints

It's difficult to give a stronger hint than what's mentioned in the preamble "appears diagonally in the grid" other than it is all but 2 letters of a main diagonal.
As you've got a complete grid you must have the source of the theme and if you want to look up the exact wording which appears (along with the referred to 6 of the 8 unclueds) without reading the source in entirety Google "The St Crispin's Day Speech".

Oh! I thought they were two distinct names. I was looking for the proclaimer AND the leader. Doh! Have already got the proclaimer! Obviously didn't read the instructions properly. 'Appears ' not appear. What a twit. Thanks.