Many times we come across examples like these :-
Hobbits are an unobtrusive but very ancient people...
For they are a little people, smaller than Dwarves... ~ From The Fellowship of the Ring, JRR Tolkien
Is the first sentence grammatically correct? To me it seems 'an' shouldn't go with 'people'. Is it just a play of language by Tolkien or a regular form. When are such phrases correct and when would they be incorrect?
In the second sentence, 'a' ruins the regular English and sounds weird. Again, are there examples from other writers? When are such sentences correct?