Riverboat,
Yes, confusion all round, which is why I tend only to use the vanilla 'cleared to land' unless the crew prompts me.
Think of the 'land after' instruction (for it is not a clearance) as a 'land at your discretion'.
Historically at Heathrow, the 'after the landing' came about because the 'land after' was being used more and more by ATC, and some airlines protested that they weren't being given a clearance to land.
Vespasia,
That's interesting, 'vacating' is not mentioned in our Part 2. But surely the whole point in the 'after the landing' clearance is to get it out of the way well before the 2nd a/c gets over the numbers? If you're waiting until the one ahead is in the process of vacating, then why not wait the extra few seconds and give a normal landing clearance?