Well, if by some mishap the Clansman doesn't work they could take a few hints from the locals. The Arabs had a working optical network from Cordoba to (I think) Libya going in the 10th century -- a chain of heliographs that could relay a message in around twenty minutes. And they used their own Speckled Jims for parcel post: one hungry chief in Morocco had his favourite Lebanese cherries delivered on the day they were ripe by tiny silk bags tied to the legs of a flock of homing pigeons. One cherry per bird (the usual allocation, I believe), and he ordered 400.
Course, things have gone downhill a bit since then. Was it £144 million the MOD spent on Bowman before realising it wasn't going to cop so much as a walkietalkie. You can get a lot of pigeons for that.
R