Move over, Meghan Markle; move over, Kate Moss. The newest style icon to have “effect” attached to their name is the soul-searching, relatable millennial Fleabag. In the aftermath of Monday night’s final episode, the titular character’s wardrobe choices have become just as much a talking point as “hot priests” – and this has proved profitable for those who design her clothes.

After the revelation that the £38 black jumpsuit worn in episode one of series two by the show’s writer and lead, Phoebe Waller-Bridge, was by the London-based label Love, the garment sold out by the end of the day. The brand, founded by the designer Teri Sallas and her husband, Lakis, in 2003 and worn by Katy Perry and Little Mix, quickly put another 500 jumpsuits into production, and these are to go on sale at the start of next week.

“At first we were thinking, ‘hang on, what’s going on?’ and then we managed to locate [why it was selling so fast] ,” says Sallas. The brand sells via the online retailer Silkfred.com, which champions independent labels and has a concession in Topshop. “It’s fantastic for us. Luckily we just had a delivery of that cloth and because everything is made in north London it is quicker to get things done.”

The red floral dress, ‘perfect for Fleabag – slightly inappropriately short hemline and good ethics’, says the show’s costume designer. Photograph: Kevin Baker/BBC/Two Brothers

Sallas hadn’t watched the show before this week, but says the Fleabag character is just the type of woman she sees wearing her clothes. “It’s strong and makes a statement. I wanted to make something that covered everything up but was still sexy – and she looks fabulous in it.”

Love has the show’s costume designer, Ray Holman, to thank for the surge in sales. After reading Waller-Bridge’s script, he headed to Oxford Street in London to source Fleabag’s wardrobe, where he found Love’s jumpsuit in the “cool basement bit” of Topshop. “I basically went out and got about two or three rails’ worth of things from various places and then had a fitting with Phoebe – it was very collaborative. We both gasped when she put that [jumpsuit] on.”

Holman’s other choices are looking to be just as popular – and not just with Waller-Bridge, who Holman says liked her character’s wardrobe so much she kept much it for herself. In the week that Fleabag ended the two-season drama wearing a red floral dress, the search engine Lyst reports that searches for red dresses are up 38% over the past two weeks.

Holman bought that red dress, which is no longer available, from the sustainable, Instagram-favourite Reformation and he says it was “perfect for Fleabag … slightly inappropriately short hemline and good ethics”.

Lyst notes that searches for off-the-shoulder dresses have increased by 23% since Fleabag stepped out with Hot Mysongist in a black off-the-shoulder piece Holman says came from Zara. He sourced the rest of Waller-Bridge’s wardrobe from affordable labels as “it wasn’t really about choosing designer names”: striped tops from Benetton; high waisted jeans from Arket; shoes, a mixture of Superga and Vans; and a trench coat from Cos.

“The essence of Fleabag is that she runs a café. She still wears high street, albeit with a huge sense of style.” The most expensive item on the show was a coat that Kristin Scott Thomas’s character wore, which Holman got from Emporio Armani on New Bond Street.

It is unclear if the Fleabag effect is limited to the lead character. There was, of course, a focus on the ecclesiastical robes worn by Fleabag’s love interest, the priest, played by Andrew Scott. Holman rented the pieces and those that made it into the show were a mixture of his, Waller-Bridge and Scott’s favourites, although unlike Waller Bridge, Scott didn’t take his costumes home.

The Priest wearing his chasuble back to front (on purpose) Photograph: Luke Varley/BBC/Two Brothers/Luke Varley

A spokesperson for Watts & Co, the Westminster-based design house that has created the vestments worn by the clergy for the last four coronations, said: “We are very busy at the moment. But would not attribute this to the show,” adding: “We could have produced some better vestments if we had designed them in our exclusive silks.”

The vestments house points out that in a vestry scene, the priest’s chasuble is on back to front – an intentional detail, confirms Holman, who was keen show off more of the embroidery.