Removing tariffs on U.K-U.S. commerce has been a priority for Prime Minister Boris Johnson’s government as
they seek a broader trade deal with President Joe Biden’s administration. Britain unilaterally dropped tariffs on some U.S. products indefinitely in January in a bid to reduce trade tensions. The former Trump administration did not reciprocate the U.K.’s concession. -Bloomberg
According to the UK, the move is a "bold, joint step" towards resolving one of the longest running disputes at the World Trade Organization (WTO), and that the two countries should focus on "addressing the challenges posed by new entrants to the civil aviation market from non-market economies, such as China"