Paul:

In Dublin and Cork pretty much every home is passed by those old co-ax systems. They're quite neatly done, generally neatly tacked tightly under the facia (just below the roof) and crossing overhead for short distances or else down and underground.. It's quite common in Cork that they run along the back walls of properties just below the cap stone at the end of the garden. They're extremely extensive networks (as extensive as the phone network), as far as I know we've some of the highest cable penetration rates in Europe, you don't see very many antennas on roofs in the cities here. The old coax systems are ok for plain old TV service either analogue or digital but often can't provide 2-way access for internet, voice and interactive services. Which is why, like sky, some of the digital cable systems require the set top box to have a phone line connection for interactive stuff.

Newer housing developments would have underground coax or coax-fiber hybrid and gradually those networks are being expanded to eventually phase out the old systems. NTL are in BIG trouble here though, they bought Cablelink and its 1.9 million customers from eircom (who were forced to sell it in an attempt to break its monopolistic practicies) and part of the licence they agreed to set out requirments for upgrading the network, however NTL worldwide is doing very badly so they stopped investing here. They may loose their Irish cable licences s they've failed to update 90% of the network.

The 2 cable companies also operate a digital terrestrial microwave broadcasting system with a mirror digital television service in the 2Ghz range.. it was originally fully analogue!

Antennas look like this:
[Linked Image from mojweb.sk]

or flat ones that look a little like this:
[Linked Image from radiowavesinc.com]

The horrible old analogue decoders used for both cable and microwave:
[Linked Image from cable-converter-box.com]