Mr. Tweed Country Style Blog
Sock Length Matters
Because with shooting socks length matter. They should of course primarily be used with breeks, otherwise you do not see them. The extra length can be used for tucking them inside your breeks, minimising the risk for that embarrassing slipped down sock. That way you do not have to tighten your garters till your feet get blue. Or just fold them an extra time over your breeks, and the extra thickness will prevent debris getting into your wellingtons.
Some last piece of advice though. Your breeks are to be fastened just below your knee (about two fingers width down). If you fasten them to low they will impair your movability and you will lose the true sporting style of the socks and breeks formula.