Readers of a certain vintage will forever associate the phrase "that dress" with the eye-poppingly skimpy Versace creation Liz Hurley wore to the Four Weddings And A Funeral premiere in 1994.

But two decades on, "that dress" has come to mean something else. For the adoring crowds who mob her, the activists who cheer her and the hundreds of thousands of Scottish women who quietly approve of her, it refers to the one Nicola Sturgeon was wearing when she was elected First Minister and in which she sat (stood actually) for the official portrait of her which now hangs in Bute House.

More than that, the dress has come to symbolize a sartorial volte face which has seen Sturgeon hailed as one of the most stylish female politicians around. Out have gone the comparisons to dowdy old Angela Merkel and her "death row haircut", in have come the cheeky suggestions that Ms Sturgeon may be channelling the style sense of Kate Middleton or Michelle Obama. There's even talk that she could be a fashion icon in-the-making, a sort of Caledonian Jackie O only with little need for sunglasses and much less money to spend.

"She's definitely become softer," says Edinburgh-based stylist and image consultant Judith Campbell. "She looks more feminine so in more respects she looks more like herself which will make people warm to her more. People say she's lost weight but I don't think that's got anything to do with it - she's just lost the boxy jackets and baggy trousers and gone for more of a figure silhouette. She's also softened her colours. The best I've seen her looking is in that raspberry dress."

There we go: that dress again.

The garment in question was designed by Edinburgh-based company Totty Rocks and was reputedly chosen for Ms Sturgeon by Ria Robertson, the woman some are calling the power behind the sartorial throne. That dress has since become a "capsule collection" of 12 dresses in various shades of coral, turquoise and plum, along with four jackets in the same colours. All are in the same triple crepe fabric, and all can be machine-washed - an important detail for the campaigning politician.

"She always looked fairly respectable and neat and tidy, but I think since becoming FM she's wanted to have more of an impact with what she wears," says Totty Rocks co-founder Holly Mitchell. Previously, she thinks, "a lot of her clothes weren't fitting her really brilliantly, and maybe kind of covering up and sometimes in they were in the wrong colours. It was all a bit harsh. She used to wear a lot of grey and red. She looks fantastic in red but I don't think the grey really suited her."

And now? "I think she looks fantastic," says Ms Mitchell of the new-look Nicola. "I think it says there's something else to her. She's not dressed in a boring boxy suit, she's wearing something that's a little bit more daring than many politicians. I think it says there' a lot more to this wee lady ... I think a neat dress and really killer heels have become her thing".