The US first lady has been widely criticised for the insensitivity of the gesture, made during a visit to a child migrant shelter on the US-Mexico border in the wake of her husband being pressured to sign an executive order cancelling the separation of children from their families as part of a “zero tolerance” crackdown on illegal immigration.

Spokeswoman Stephanie Grisham told reporters there was “no hidden message” behind the selection of the jacket, which is sold by high street retailer Zara for $39 (£29).

But Donald Trump immediately contradicted this stance on Twitter, suggesting the coat was an expression of his wife’s disgust at the “Fake News Media”.

Ms Trump has been the subject of much scrutiny in recent weeks over her absence from public life.

Last month she underwent a kidney operation but has since appeared reluctant to attend functions and been seldom seen, eventually issuing a tweet to address press speculation about her whereabouts.

“Rest assured, I’m here at the White House w my family, feeling great, & working hard on behalf of children & the American people!” she wrote.

Following her husband’s inauguration in January last year, Ms Trump preferred to stay in New York City for several months rather than join him living in Washington, DC, stating a desire to shield their son Barron – then 10 – from the media’s glare.

She has cut a reserved figure ever since, preferring to work quietly on her anti-bullying agenda – the subject of much satire because of her husband’s aggressive approach to going about his business.

When she has played the hostess, many of Melania’s efforts have passed off without a hitch but she has often been mocked: notably over accusations her cyberbullying pamphlet was no more than a reprint of an Obama-era forerunner with a new cover and for her “creepy” Christmas decorations.

An unintentionally surreal oak tree-planting photo op on the White House lawn with France’s Emmanuel and Brigitte Macron this spring was also the subject of much ridicule.

For her part, Ms Macron told Le Monde she found Melania to be “very fun” in private but so hamstrung in her behaviour as a result of the scrutiny she is under “she can’t even open a window”.

Melania’s frequent habit of batting away her husband’s hand whenever he attempts to hold her’s on official visits has meanwhile led to whispering that their marriage is an unhappy one.

Donald Trump and Emmanuel Macron plant an oak tree watched by the US first lady, Melania Trump (Jim Watson/AFP/Getty) (AFP)

The responsibilities of a first lady are only loosely defined and how the current incumbent enacts it depends very much on their personality.

Operating with their own White House staff, first ladies can take a prominent political campaigning role, champion specific social causes they feel passionate about or play a ceremonial part on occasions of state.

While Ms Trump’s predecessor, Michelle Obama, was a tireless presence in Washington, the wives of presidents George HW Bush and his son George W Bush, Barbara and Laura Bush, both preferred to focus on their pet causes: literacy and women’s rights.

Other notable campaigns include Lady Bird Johnson pursuing environmental pollution, Pat Nixon promoting volunteerism, Nancy Reagan’s foray into the war on drugs and Hillary Clinton’s ambitions for healthcare reform.

Dolley Madison (1768-1849), wife of the fourth president James Madison, is credited with setting the template for first ladies to follow by furnishing the White House, working to help orphans and women and attracting press interest due to her modish manner of dress. She was given an honorary seat on the floor of Congress and her popularity contributed enormously to her husband’s appeal.

Her example is said to have abided until Eleanor Roosevelt’s tenure, barring the extraordinary case of Edith Wilson, forced to run the executive branch of government between October 1919 and March 1921 after her husband, president Woodrow Wilson, suffered a debilitating stroke and was left bedridden. Nancy Reagan is also said to have come to husband Ronald’s aid on multiple occasions when his health was failing.

Ms Roosevelt, serving as first lady between 1933 and 1945, redefined the role entirely thanks to her outspoken character.

Ahead of her time in her attitudes to race and gender, Eleanor Roosevelt held regular press conferences, wrote regular newspaper and magazine columns, hosted a radio show, spoke at party conventions and was never afraid to publicly disagree with her husband’s policy agenda.

The pressure for first ladies to be picture-perfect matriarchs perhaps stems from the impossibly high standards of glamour Jacqueline Kennedy set in the early 1960s.

Sevnica: Melania Trump's home town Show all 18 1 /18 Sevnica: Melania Trump's home town Sevnica: Melania Trump's home town The 12th-century castle dominates Sevnica old town Getty Images Sevnica: Melania Trump's home town The old town has a beautiful riverside setting Getty Images Sevnica: Melania Trump's home town 'White House' slippers in Sevnica castle Nick Redmayne Sevnica: Melania Trump's home town The annual salami festival, the Salamiada Nick Redmayne Sevnica: Melania Trump's home town Sevnica was a nondescript town before Melania hit the big time AFP/Getty Images Sevnica: Melania Trump's home town Sevnica butchers take their sausage-making skills seriously Nick Redmayne Sevnica: Melania Trump's home town Only men are allowed in the Salamiada Nick Redmayne Sevnica: Melania Trump's home town As American as.... a Sevnica apple pie Nick Redmayne Sevnica: Melania Trump's home town There are no plans to make a Donald pie Nick Redmayne Sevnica: Melania Trump's home town The slippers featured in a recent fashion show AFP/Getty Images Sevnica: Melania Trump's home town The castle is one of the top tourist sites in town Getty Images Sevnica: Melania Trump's home town Melanija cake has gone down a storm AFP/Getty Images Sevnica: Melania Trump's home town The smart house still owned by Melania's parents Nick Redmayne Sevnica: Melania Trump's home town They live in America but visit occasionally Nick Redmayne Sevnica: Melania Trump's home town The communist block of flats in which Melania grew up Nick Redmayne Sevnica: Melania Trump's home town Melania skin cream, for a presidential complexion Nick Redmayne Sevnica: Melania Trump's home town First lady chocolates, dusted with gold Nick Redmayne Sevnica: Melania Trump's home town Even locals can't get enough of the Melanija cake Nick Redmayne

This superficial sheen of perfection is hard to maintain and the extraordinary pressure and scrutiny the presidency attracts can inevitably take a toll on a marriage.

The humiliation Hillary Clinton suffered when news of her husband Bill’s affair with intern Monica Lewinsky broke in 1997 was made doubly hard to bear because the eyes of the world were watching.