This was the standard knot I used as a University of Waterloo coop student in the mid 80s. Let's see if I remember how to do this. I have a tie in hand, Here we go...
- Put tie around neck. The small end is to my left, not quite 1/4 of the tie's length is on that side.
- I cross the fat end over the small end, and then fold the fat end underneath. Now I can see the "Surrey ties" tag on the back of the fat end.
- Now I bring the fat end through the loop of cloth around my neck, from the front and out the back. The fat end is still to my right and I can still see the tag. So far, so good.
- Now I cross the fat part over the proto-knot, concealing it. The fat part comes around, behind and through the loop around my neck, on the left side. Then it goes out the front, under the knot-concealing loop and out the bottom.
- I pull it tight and Ta-da! A servicable Half-Windsor.
Not bad, it's the first time I've done that in a year or so.