] ..in looking at a couple of Ag Rev books this week, I discoverd that many "rents" were not at all like we have them today. Instead, people paid a lump sum (quite large) in advance, rented for a fixed time, and the annual and quarterly payments would be very small indeed. I've got no figures, I'm afraid- this arrangement was in relation to renting farms mostly, not estates.

So this could possibly explain why Bingley didn't give Netherfield up completely when he returned to town... if he'd already paid the larger part of his lease, then he might as well hang on to it until the lease was up, maybe?