During an official visit to the United Kingdom in 2018 by U.S. president Donald Trump, an inflatable caricature of Trump (colloquially known as the Trump Baby or, less commonly, the Baby Trump) was flown in protest of his visit, his history of alleged sexual misconduct, his leadership style and his policies.

The balloon was flown over Parliament Square, London, on 13 July 2018, where the police estimate that over 100,000 protestors were in attendance, and 50,000 more in the Meadows, Edinburgh, the following day, where protests were also held. Although Trump was not visiting Edinburgh, he was spending the weekend at his Turnberry golf course, but permission to fly the balloon there was refused by Police Scotland.

One of the organizers, Max Wakefield, described the balloon protest as being in response to "the rise of far-right politics that dehumanises people in order to get into power", and saw it as an attempt to introduce some "good British humour" into the political discourse surrounding Trump's visit. Wakefield cited the Trump administration's family separation policy and Trump's withdrawal of the United States from the Paris climate agreement as examples of the kind of policies which the protest was targeting. Leo Murray, who led the campaign, wrote in its crowdfunding statement:

[When] Trump visits the UK on Friday the 13th of July this year, we want to make sure he knows that all of Britain is looking down on him and laughing at him. That's why a group of us have chipped in and raised enough money to have a 6 meter high blimp made by a professional inflatables company, to be flown in the skies over Parliament Square during Trump's visit.

The 6-metre (20 ft) tall, helium-filled plastic inflatable, also referred to as a "balloon" or "blimp", was designed by Matt Bonner and constructed by Imagine Inflatables of Leicester. It was made after a crowdfunding campaign on Crowdfunder raised the £16,000 cost of its creation and deployment. It depicts Trump as "an angry orange baby" with a snarling mouth, tiny hands, wearing a diaper, and holding a smartphone.

Wakefield said, "The only way that you can make any impact with Donald Trump is to mock him, because you can't engage him in any kind of argument — it never gets anywhere."

Permission from the Greater London Authority (GLA), Metropolitan Police and National Air Traffic Service (NATS) was required for the balloon to be flown over Parliament Square, the space above which is considered restricted airspace. Permission was granted, allowing it to be flown, while tethered, up to 30 meters (100 ft) high, for up to two hours. Both the GLA's 'City Operations' team and NATS stressed that the nature of the protest did not play a part on their decisions.

After learning of the balloon, Trump remarked, "I guess when they put out blimps to make me feel unwelcome, no reason for me to go to London."