With her many recent outfits – including her wedding dress – rented, she has made her passion for sustainable fashion clear.
Now, Carrie Johnson has delved back into her own wardrobe by recycling a red blazer from Zara for the G20 summit in Italy.
The prime minister's wife, 33, first wore the affordable item at the Conservative Party Conference in Manchester earlier this month.
This weekend, the pregnant mother-of-one slipped it back on to dress up her growing baby bump as she stepped out at the Colosseum in Rome.
Johnson paired the stylish blazer, which costs £59.99, with a thigh-split red rose-patterned midi-dress by Spanish designer De La Vali – rented for £53 from Hurr.
According to the Zara website, the formal jacket has a fitted style, with a double-breasted fastening and embossed metal buttons.
It also comes in steely blue and camel brown, and is still available online in certain sizes.
Finishing off her look, Johnson, the senior advisor to charity Oceana, wore a black face mask, as well as pair of sling-back red kitten heels, with a red handbag slung over her shoulder.
Johnson also wore a £210 necklace by London-based jeweller Philippa Herbert, featuring her one-year-old son Wilfred's fingerprint, that was a Christmas present from her husband.
She recently wore the statement blazer at the Manchester Central Convention Complex on day three of the Conservative Party's annual gathering.
On that occasion, Boris Johnson's partner paired it with a £27.99 Zara shirt, and a pair of black jeans and heels.
It is similar to a textured red blazer, also costing £59.99 from Zara, that Kate Middleton wore to Euro 2020 earlier this year.
Johnson is currently expecting her second child, and she is thought to be due to give birth in December after revealing that she hoped for a "rainbow baby" this Christmas.
In July, she shared on Instagram that she felt "blessed to be pregnant again" after experiencing a miscarriage earlier this year that left her "heartbroken".
The mother-of-one wrote: "Fertility issues can be really hard for many people, particularly when on platforms like Instagram it can look like everything is only ever going well.
"I found it a real comfort to hear from people who had also experienced loss so I hope that in some very small way sharing this might help others too."
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