Thank very much for you comments so far.
The reason I ask is as follows. There is a company coming to the market in the next few months that offers the empty legs but with a very clever bit of software. The way is works is as such. Say an AOC is flying a one way Cardiff to Inverness then flying back empty. The AOC enters the empty leg on the online system (and his hourly rate cost of the particular aircraft), and other AOC's flying empty legs (hopefully) do the same all over UK.
Say Mr Rich Punter wants to go from Glasgow to Bristol, his broker would generally look for operators near either end of dest/dep to do this flight and Mr Rich Punter pays the whole return journey.
If the broker uses the system explained above the system automatically calculated the diversion costs of a suitable aircraft of all empty legs in the area to and from dep/dest airports and the system finds the one most suitable, if there are any. Negotiations then take place between broker and AOC of actual costs and who gets what. There is actually no reason to discount the leg as the Mr Punter knows no different, he gets an aircraft turn up and take him to where he wants to go. He gets his aircraft and the AOC and broker make more money and the company managing the matching system taked a fee.
If the original legs is cancelled the empty leg now pays for itsself and the AOC has another empty leg to sell.
Any thoughts ?