Another possibility for subordinate clause without subject

[vpkannan]

Dear Alan

I beg to differ from you. Can I interpret the sentence 'More people came than had been expected' as follows:

'More...than' is correlative conjunction like 'both ... and' or 'either ... or', and 'than' acts as a coordinating conjunction part of the correlative conjunction like 'and' and 'or'. Therefore, 'than' joins two finite verbs, viz., 'came' and 'had been expected', two parallel constructs.

[Alan]

I'm afraid that your suggestion does not conform to any analytical norms with which I am familiar. 'Than' is never classified as a coordinating conjunction.