In both the Royal & Ancient guidelines and the United States Golf Association (USGA) 'Pace of Play' comes under the 'Etiquette' section as opposed to 'Rules' and both say pretty much the same thing ie that ...if you have lost a hole between you and the group in front you should give way to the group behind.
A couple of points to make:
1/ Whilst not strictly rules, to most players, the items in the etiquette section of the rule book as as important as the actual rules themselves.
2/ Note that the reference in the etiquette section as to what to do in the instance of slow play refer to 'groups' ie a slow 'group' should let a faster 'group' play through. Hence you'll hear people saying... a single golfer has no 'standing' on the course ie the single player will not be let through a group and would be expected to let a 'group' play through if they caught up to the single player.
I think that's about right (unless of course someone knows differently!)
-- 02/04/2008 09:45:55: post edited by pconnon.