OK, yes, the Air traffic controller should really be telling you to expect a hold, but on the rare occasion it may get forgotten, we rely on the fact that the clearance limits in your STAR charts is the hold you are inbound to. Why is it then that there are so many pilots just recently that seem to be unaware of this fact? It can be a safety critical thing for us.
If you allow for the "rare occasion" the controller "forgets," and the less-than-100% of those times where the pilot fails to hold, then you surely must allow for that "rare occasion" when the pilot "forgets" as well...
If it is so safety critical, then the controller must not "forget," either. After all, he's the one sitting on the ground with his tea...
More seriously, though, I have not seen another STAR quite like those I just looked at for Gatwick (I seldom go to London; Stansted when I do). While the STAR chart is clear, it is a bit unusual for a STAR to end in a hold; and even more unusual to be cleared for a STAR and not be alerted of any hold well in advance.