Royal Mail Charters
Rumour has it that the Royal Mail are in the processing of restructuring the the Mail Flight Operation throughout the UK.
The latest word is that instead of having lots of SH36s (and similar) bumbling around the UK from the airports they currently serve, the mail will be put into the cargo containers at the regional sorting offices, then driven to a nominated major UK airport, to be flown onward.
Given that in order to meet its government charter commitments, Royal Mail operates strict deadlines for the current charter operators to leave and arrive by, I don't see how they'll improve on this - or make it significantly more economic - by using more road transport, larger planes and fewer airports.