Although there is a good deal of variation in the methods and styles of the top tournament stars, there is one fundamental, I have observed, that is common to all of them. This is the head position at impact. At the moment they strike the ball, the head is positioned two or three inches behind the ball.
The large majority of golfers, struggling to improve their games and more often than not finding this very difficult, have no idea where their heads will be at impact. The average golfer habitually thrusts his head ahead of the ball—and slices the shot. Sometimes he is addicted to the opposite extreme: his head is a good many inches behind the ball at impact—which encourages hooking. For that matter, it is not uncommon for the average golfer to alter the position of his head from day to day or, even, from swing to swing. This defeats the very thing he is trying to get: consistently accurate shot production based on a steadfast "groove."
The time to get the head set properly, of course, is at the start of the swing when you are addressing the ball. Line yourself up so that your head is two or three inches behind the ball and anchor it there surely, not tensely but firmly. It's a key position.
from PETER THOMSON, British Open champion, 1954 and 1955