tj, this might answer some of your questions: look on p. 135 of David's most recent book on uniforms covering modifications of the Denison smock. He states that special modification of the smock was approved for snipers on Feb. 24, 1945 which was the addition of an oversized external patch pocket on the left side of the smock's skirt. The modification was done at the unit level with materials scavenged from other smocks. The modification was optional and required the sniper's CO's permission. Another unofficial modification was sewing a short length of a Vicker's fabric machine gun belt to the forearm of one of the smock's sleeves to hold ammunition which could be accessed with a minimum of movement. There is no mention of a watch or compass pocket.
If you look on p. 265 of the same book David shows two leather lanyards that were private purchase popular with officers and NCOs to carry a watch, compass, or whistle. The single lanyard was made of leather and had a hole in each end, one to fit over a button, the other for attaching whatever to. The double lanyard was favored by officers of the Ox and Bucks when wearing battle dress.
Some people have confused the camoflaged windproof smock with the Denison smock which can lead to confusion although the two are quite different.