Home Secretary Theresa May is said to have personally reviewed the case of Filimone Lacanivalu, a Fijian ex-soldier threatened with deportation, and decided last night that he could remain in the country.
The 34-year-old, who was part of the British Army for nine years, served with the 2nd Battalion the Yorkshire Regiment in Afghanistan, Bosnia and Northern Ireland.
More top news
The incident is not believed to be terror-related, British Transport Police said.
The royal couple have been in the US to mark the 300th anniversary of the foundings of New Orleans and San Antonio.
A small number of people were treated at Southgate Tube station, British Transport Police said.