Originally William Noel Downing joined the 21st Battalion of the Royal Fusiliers (4th Public School) as a private. The battalion was first of all stationed and underwent training in Ashtead Surrey. A number of photos and letters have survived. A group of letters to his sister Mary give a picture of his billets and training activities in this period. 

There is also one undated letter from Noel to his mother written on headed 21st Royal Fusilier's notepaper. Here he bemoans the chaos in allocating kit and accommodation in the huts. The battalion was deployed to France in Nov 1915, but only saw limited action. The battalion, drawn from English Public schools and universities, was disbanded in April 1916 as many of the men took up commissions.

Noel Downing himself was gazetted in the Welsh Guards on 4 August 1916 and ordered "to report to Buckingham Gate forthwith".

He appears to have completed the probation period for his commission as a second lieutenant, Special Reserve Officer, in November 1916.

Noel Downing, in common with most of his contemporaries spoke little about his experiences in France. He returned to France with the Welsh Guards in about October 1916 after his change of regiment. He did recall to his daughters stories about his uniform coming back from laundry with the lice pressed into the creases.

One letter written to his future wife, dated 11 November 1916 has survived. Here he is fairly stridently against the war saying how he hates the army. Much of the letter is in sympathy with Molly Evans, who finally took the decision to resign from the VAD in France and return to her sick mother. Molly's brother, Wilmot Evans, had been killed on 1 July 1916 and Noel shows little patience for the Army Officers and their relatively comfortable existence away from the trenches.

The buttons and insignia of his Welsh Guard uniform have survived.

There is also a large collection of humorous publications that show that he kept his spirits up by trying to see the funny side of some of the more awful things going on around him. viz. Pow Wow army news sheet and Bystander magazine as well as bound copies of Punch from the wartime years.

It is evident he spent a period in early 1917 unfit for combat because of deafness, described in a letter to his sister Mary.

Noel Downing was demobbed sometime between Jan and April 1919 and got married to Molly Evans in July 1919.