This chap might be quite tricky for someone to track down having moved to the States. Hopefully this will help someone in the future.
"TOO LATE. DYING MOTHER'S WIRELESS TO HER SON. Mr. Arthur Underwood, of Cheyenne, Wyoming, a British subject by birth, but an American by naturalisation, was granted special perission to land at Southampton on Friday, although his passport was without a British visa. He came across the Atlantic in the Leviathan, intending to go to Bremen, in Germany, but a wireless message summoned him to the bedside of his mother, 83 years of age, who was dying at Wellingborough. Mr, Underwood served with the British Army in the Zulu war. His mother, Mrs. Bryant, of Alma street, Wellingborough, died before he could arrive there, and was buried on Friday."
Northampton Chronicle and Echo - Saturday 15 September 1923
Believed to be Private A Underwood 3/60th.
Duttons p291 has him as 988 A Underwood 1879 clasp however his number was really 415 (see below) which Dutton has assigned to T Usherwood the next man down so these need to be swapped in the book.
(Just suprised myself and learnt how to do copy records like this into a forum page

. Not back for a woman stuck in the 19th Century!!!)
[You must be registered and logged in to see this image.]Discharged 31 August 1882
"The Trail to England. A British-born American known as Old Cap Underwood hurried across the States and the Atlantic in such haste to visit his dying mother at Wellingborough that he forgot, to have his passport vised. Two famous Americans, Mr Harvey, the Ambassador. and Mr W. H. Hays, the maker Presidents, pleaded his case with the transport officials in order to prevent him from being turned back. It might be captious to ask if a visitor from this country would in similar circumstances have found an easy way into the States. Underwood, who is now 61, is accustomed to adventure. He left his native place at the age of seventeen to fight in the Zulu War, and subsequently roamed over the world, finally settling in the West. When he received a cablegram about his mother, whom he had not seen for thirty years, he was hunting grizzly bears in the Rocky Mountains. Immediately the handsome man of powerful physique and snowwhite hair packed his kit and "hit the trail " for England."
Aberdeen Press and Journal - Thursday 20 September 1923
"BRITISH-BORN AMERICAN. Difficulties Homecoming. Two well-known American statesmen pleaded the case of well known British-born Amercan before passport officials in the library of the United States liner Leviathan at Southampton in order keep him from being turned back to America after a 6,000 miles journey to visit the bed of his dying mother in his native birthplace Wellingborough, Northamptonshire, because his passport was without a visa. The two statesmen were Mr. George Harvey the American Ambassador, and Mr. Will H. Hays, while the man for whom they pleaded was old Captain Underwood, soldier of fortune, celebrated in the days of the “"wild and woolly West" in the United States, and the oldest living aviator. Old Captain Underwood, whose real name is Mr. Arthur A. Underwood, was hunting grizzly bears little over two weeks ago in the Rocky Mountains when he received a cablegram, to return his native birthplace to see his dying mother, and answered the message so quickly that in his haste forgot secure the necessary visa for his passport. I have not seen mother for upwards of thirty years,” said old Captain Underwood in interview. ‘‘Gosh, it does seem darn funny to be back England after all these years, it is hard believe that a country could be so beautilul.” He left Wellingborough when he was 17 years old to join the army to fight in the Zulu war, and since then he has lived in and visited practically every country in the world, finally settling down in the West."
Belfast News-Letter - Friday 21 September 1923
Reminds me of that famous tracker from the Old Wild West they named the knife after.
Jim Bread