Am I correct in assuming that this phrase ie give him the whole 9yds originated in the First World War as my grandfatrher who fought at Gallipoli used to sat it with monotonous regularity comes from the length of the webbing on a Vickers Machine gun which apparently is 9yds long
Or am I mistaken and owe him an apology.....
Have a look here http://www.worldwidew...rticles/nineyards.htm Paragraph 4 provides a good list of possible sources, but the whole article is from a well-known etymologist and is well worth reading. Your grandfather's suggestion is just one of a multitude, I'm afraid!
those links suggest it wasn't recorded before the 1960s, so if your grandfather knew the phrase earlier than that, he might well have been on to something.