Several ostensibly grassroots organisations found their voice this week with expensive advertisements against same-sex marriage as the Coalition met to discuss the issue.

The campaigns were eye-catching, but what they did not freely disclose were links to a more powerful moneyed lobby, the Liberal Party and even the Prime Minister himself.

Ashley Goldsworthy is a director of Marriage Alliance. Credit:Robert Rough

TV and online ads – including on Fairfax websites – compared the legalisation of same-sex marriage to an iceberg and said the change potentially carried negative consequences for children and human rights.

The campaign was paid for by a group incorporated a month before the ads hit airwaves: Marriage Alliance, which also commissioned polling reportedly showing same-sex marriage was a low priority for voters ahead of Tuesday's government party-room vote.