Rams Head Antiques has dated this piece to the 1910s.
Ashenden was an officer of the Royal Field Artillery.

Ashenden's entry reads "For conspicuous gallantry and devotion to duty. Whilst the battery was retiring along a road crowded with transport of all kinds, hostile infantry brought machine-gun fire to bear on the column, causing considerable confusion. This officer, who was commanding the battery at the time, immediately extricated it from the press of the vehicles, and brought it into action in the open. He then collected some infantry to hold the line by the guns, and thus covered the retirement of the transport."

To find this entry for yourself, simply go to the London Gazette website, click "All Notices, click on text search on the left and enter "Harold Campbell Ashenden" and then open Supplement 30901.
The sword is in excellent condition throughout. The leather scabbard is in good original order. The fish skin grip is perfect and all of its wire binding remains intact. There is some very minor areas of rust pitting to the three-bar hilt, as you would expect from a steel-hilted sword. The original leather sword knot is present, as is the frog strap which Ashenden hand-wrote his name onto (see photo 4). The single fullered, spear-point blade is in good condition with virtually no pitting. The ricasso of the blade is etched with Ashenden's initials, and is stamped with a government proof mark. The blade also bears the cipher of George V.
Overall length 106cm. Blade length 89cm.
Rams Head Antiques has dated this piece to the 1910s.
You can view the stock and full dealer information on the Rams Head Antiques Profile Page