I believe the last time I wore that uniform was in 1974 or thereabouts, and our knee socks were solid green- something closer to faded fatigue / OD, but called Khaki in the British sense. We wore them with garters and flashes.

For the sasquatches who like Boy scout socks, here is a deal:

http://www.scoutstuff.org/BSASupply/ItemDetail.aspx?cat=01RTL&ctgy=PRODUCTS&c2=UNIFORM S&C3=USOCKS&C4=&LV=3&item=BSKS&prodid=BSKS^8^01RTL &