80s Channel 4 Commercial Breaks....

Either no ads sold, possible late night in a small region, a break down of the cart machine at that region (more likely), the operator falling asleep (a TVS operator told me he did that once at about 2am waiting for a C4 break) or a BT circuit failure meaning the IBA/BT rerouted the feed direct from C4 to the Tx (happened a few times in the TVS region).

In 1988 we had the opposite. The BT Tower to Southampton SHF links failed, affecting all four channels. BBC 1 and 2 were restored in seconds thanks to RBS, TVS managed to reroute their network feed from via Maidstone, but C4 was dead for about 2 hours. However, TVS still inserted commercial breaks at the planned times.
They did manage after about 10 mins to get a locally generated apology slide up.

The lost C4 programme that night, was the first part of a drama series, 'A Very British Coup'. TVS ran that episode on the following Sunday night, on TVS if I recall correctly.

I don't know for sure, but I suspect that may have had something to do with the fact that chunks of the South West couldn't get 4 for the first year or two. (I was watching on Beacon Hill's feed at that time and we certainly didn't see it initially.)

Much like some of the South West later couldn't get 5. Not sure why it's been so affected (transmitter overlaps?)

You're right, only two of the five main transmitters in the TSW region carried C4 from the outset. Caradon Hill, (primary target Plymouth) and Stockland Hill (primary target Exeter). However both those cites have relays that many viewers use (Plympton and St Thomas) so you're right C4's available audience was very low in the region.

The IBA had planned for the national coverage to be much higher, but they were forced to divert funds away from the C4 network, to provide almost universal coverage for S4C in Wales. All six Welsh main stations were equipped from the outset, and almost 100% of relay stations. This impacted on C4 in Eng/Scotland/NI where about a third of main stations were not equipped for 6-18 months, and virtually no relays, (only those that were recently built in the 9 months running up to Nov 1982)

It took five years for the IBA to equip the last relay station for C4, Gunnislake in the Tamar valley.

Mind you the roll out of C4 was much faster than BBC 2's 20 years earlier !

How did Channel 4 get to the Channel Islands? Was it via Stockland Hill (and later Rowridge)? Is it true that CTV didn't insert any ads onto Channel 4, and the mainland transmitters carried selected ads in their breaks aimed at islanders?

As far as I know the Channel Is C4 feed was just taken from Stockland, and then from 1984 from Rowridge, I don't think CTV inserted anything locally ?

However at 09:30hrs on Fridays the C4 test card was interrupted for a barrage of national ads. They only appeared on Rowridge, Hannington, and Midhurst, so I assume it was to send CTV last min national ads ?

From Jan 1st 1993, the day C4 stated selling and transmitting its own ads, The Channel Isles were fed by a BT fibre circuit. BT provided a new national digital fibre national distribution system for C4, replacing the analogue SHF links.

That's interesting - how come Channel weren't able to piggy back that fibre link for their dirty feed of Meridian?

I think they were, but shorly after,

Up until Dec 31 1992 all four channels were fed off air.
BBC 1 and 2 from Stockland, ITV and C4 from Rowridge.

It took the Beeb another 10 years to ditch off air reception, the Astra 28 feeds came on line around 2003

A question about PRS/royalties and the C4 sustaining feed: Library music was played at every commercial break point but, certainly as time went on, most of the time no viewers heard it because of the adverts being inserted. Would they still have to pay in these cases?

If it was 'library music' it would have been royalty free - that is the point of library music

I didn't realise that. Just been reading up on how it works.

I assume, however, they had to pay David Dundas for the use of Four Score / Four Score Two when played, as they did with for each ident sting?

I wouldn't have thought so, the tune was essentially a jingle package commissioned for the station. No different to a radio station's jingle package. Just the initial one off fee ?

According to Wikipedia (and other sources), Dundas was paid £3.50 every time the four-note sting was played, which ended up costing C4 about a grand a week, and this is stated as being the reason the jingle was re-recorded around 1991. It does seem surprising that this was the case - assuming these stories are true - but apparently there were court cases and the like regarding the ownership of the track/jingle!