Australia's most populated state is also the most divided in the nation when it comes to the same-sex marriage postal survey results, with 42 per cent of respondents in NSW voting No.

Like every other state or territory in Australia, the majority of respondents for the survey in NSW returned a Yes vote.

What has people scratching their heads, at least in the first hours of processing the postal survey results, is why the state recorded a No vote of 42 per cent, the highest in the country.

Perhaps most striking is that of the 17 electorates in Australia to return a majority No vote, 12 are located in western Sydney.

Nine of these are held by Labor, including the electorates of senior MPs Tony Burke (Watson) and Chris Bowen (McMahon) which both returned Yes votes lower than 35 per cent.

This also includes the electorate with the highest percentage of No voters in Australia: Blaxland, held by Labor MP Jason Clare since 2007, where nearly three out of every four respondents voted no.

Contrast this with Warringah, the seat in north Sydney held by Tony Abbott — a senior figure with the LNP's right wing and a leader for the No campaign — which returned the fourth-highest Yes vote in the state, at 75 per cent.

So what to make of these results?

ABC election analyst Antony Green said these results indicated that so-called "conscience" issues in Australia tend to move along cultural and religious lines rather than the class-based issues which tend to define national politics.

He pointed to the high proportion of the population in NSW born in non-English-speaking countries as an indication of the cultural differences.

"Gay marriage doesn't fit into the Australian political structure very well, because it's not a class-based issue," he said.

"It cuts across party lines, which is why the parties themselves have struggled to deal with the issue in recent years.

"NSW has, by far, the highest proportion of people born in non-English-speaking countries. In other words, there are other political cultural issues there in the mix in the debate in politics.

"I think that's what you're seeing in those western Sydney results. I understand there's been some quite specific campaigning within the Muslim community, the Chinese community, in parts of western Sydney — and that's something that goes under the radar."

What does this mean for local MPs?

Blaxland MP Jason Clare, whose constituents voted overwhelmingly for no, confirmed he still intended to vote in favour of a same-sex marriage bill.

"I'm not surprised, Blaxland is a very socially conservative electorate," he said.

"I've always known the views of my electorate on this issue and I've always been upfront with them about mine.

"Good people with good hearts can have different views on this important issue."

It wasn't all No. People and their pups celebrated at Sydney's official Yes campaign event at Prince Albert Park. ( ABC News: Riley Stuart )

And before any political operatives from the major parties think the result is an early indication they can get rusted-on voters to switch allegiances, Antony Green said the results were not the beginning of a major shake-up.

"As a political scientist, does this indicate some sort of cleavage, some sort of change, in political voting patterns? I don't think so," he said.

"Blaxland, Watson and McMahon are not suddenly going to be winnable for the Liberal Party because of these sorts of issues."