In this task, you're given a passage, further information available on a particular linked term from the statement, and a question. Your job is to generate the answer to the question by using the information provided. If there is no clear answer obtainable, output 'none'.
Example: Passage: The group was occasionally diverted from strategic missions to carry out air support and interdiction missions. It supported Operation Overlord, the invasion of Normandy by attacking transportation targets, including bridges, along with airfields and strong points in France. On D Day, the squadron and the rest of the 446th Group led the first heavy bomber mission of the day. The 446th aided ground forces at Caen and Saint-Lô during July by hitting bridges, gun batteries, and enemy troops. During Operation Market Garden, the attempt to seize a bridgehead across the Rhine in the Netherlands, the 704th dropped supplies to allied troops near Nijmegen. It struck lines of communications during the Battle of the Bulge. During Operation Varsity in March 1945, it supplied ground and airborne troops near Wesel. The squadron flew its last combat mission on 25 April 1945 against Salzburg, Austria. The group had flown 273 missions and had lost 58 aircraft during the war,
. Link Information: Operation Market Garden was a failed World War II military operation fought in the Netherlands from 17 to 25 September 1944. Question: When did the operation during which the 704th dropped supplies to allied troops near Nijmegen begin?
Example solution: from 17 to 25 September 1944
Example explanation: The passage describes the 704th's actions during Operation Market Garden, and the answer specifies when the operation happened.

Problem: Passage: Stanford was commissioned into the Welsh Guards in 1987 and saw active service during the Troubles in Northern Ireland for which he was appointed a Member of the Order of the British Empire in October 1993. He went on to become commanding officer of 1st Battalion the Welsh Guards in which capacity he was deployed to Bosnia and Herzegovina on peace keeping duties in 2006. He was the Field Officer in Brigade Waiting and commanded the parade in Trooping the Colour 2007. In 2009 he was succeeded by Rupert Thorneloe just prior to the battalion's deployment to Afghanistan and the latter was killed in action during Operation Panther's Claw. He saw active service during the Iraq War when he served as an advisor to the Head of the Iraqi Army in 2009. He became Chief of Joint Fires and Influence Branch at Headquarters Allied Rapid Reaction Corps in March 2012 and General Officer Commanding Support Command in June 2015. He became Senior British Loan Services Officer, Oman in October 2017.
 Link Information:  The conflict began in the late 1960s and is usually deemed to have ended with the Good Friday Agreement of 1998.  Question: How long had the Troubles been going on when Standord joined the Welsh Guards?

Solution: Answer: 20