Lamont, a self-described feminist who has long campaigned for gender equality, defended the broadcast despite widespread criticism of its portrayal of a mother in a kitchen deciding over a cuppa to vote No.
At a meeting of women voters organised by Better Together last week, where some members of the audience commented unfavourably on it, Lamont defended the advert to the Sunday Herald.
She said: "What struck me about it was, I've met women like that on the doorstep. What that woman said reflects what's being said to campaigners.
"I thought it was a very interesting idea. I wouldn't expect the Yes campaign to like it."
Asked if was patronising, she said: "I met a couple of women one Saturday morning on the southside of Glasgow, both of them don't knows; one nearly a No, one nearly a Yes. Young women with families with children running about them, and they were tensed in the argument. I think all that [advert] did was capture that."
Margaret Curran, the shadow Scottish secretary and Labour MP for Glasgow East, also said the advert reflected genuine doorstep conversations, adding: "I did not find it patronising. I liked the advert. I thought the advert was fine."
The Herald, the Sunday Herald's sister paper, reported yesterday that Labour insiders were blaming shadow foreign secretary Douglas Alexander for the row.
A senior party source was quoted saying that Alexander, who is also Labour's General Election co-ordinator, had angered colleagues with the portrayal of Better Together "as a 1950s-style Conservative and Unionist Party".
The source said: "He has not even had the guts to come out and defend it, using female MSPs to justify this colossal error."
An online petition has been set up demanding an apology from Better Together chairman Alistair Darling for the "offensive" advert.