This is taken from The Guardian:

BBC fails to air Shipping Forecast for first time in more than 90 years
Radio 4 suffers technical fault meaning World Service broadcast instead of weather forecast that first went on air in 1924
by John Reynolds and Mark Sweney
theguardian.com, Friday 30 May 2014 08.41 EDT

It was early-morning chaos and warnings of impending armageddon when BBC Radio 4 failed to broadcast the Shipping Forecast for the first time in more than 90 years.

The BBC radio service is something of an institution, metronomically broadcasting four forecasts a day since 1924, a routine which failed for the first time at 5.20am on Friday.

A technical glitch meant the BBC's World Service was played in its place, a gaffe that prompted listeners to take to Twitter to voice their bewilderment.

Kirsty Connell said: "Eep. The shipping forecast didn't get broadcast on @BBCRadio4 this morning. Isn't that the sign of impending nuclear armageddon?"

Jordan Rowland added: "No shipping forecast? If UK submarines don't get shipping forecast, don't they launch nuclear attack?"

The BBC was only able to resolve the issue at 5.40am when it cut back to the Radio 4 programme. Friday morning's Shipping Forecast eventually aired 6.40am.

BBC Radio 4 presenter Kathy Clugson apologised for the mistake, saying: "You're listening to BBC Radio 4. Our apologies. It's 5.40am and we've been happily broadcasting News Briefing. But unfortunately due to a technical error, you've not been hearing us, so you have been hearing the BBC World Service.

"We're sorry about that. We're looking into it and we'll try and broadcast the Shipping Forecast for long-wave listeners during the course of the Today programme."

But for some the damage to their established morning routine had already been done.

"Confused by Radio 4 failing to start broadcasting at 5.25 this morning," tweeted Graham Patterson. "No shipping forecast, no shipping forecast, no bbcnewsbriefing. Bad start to a Friday."

The incident also allowed for a predictable link to headline-grabbing UKIP leader Nigel Farage.

Mark Johnston tweeted: "Nation in peril? BBC radio fails to broadcast shipping forecast this morning. Expect Farage to blame Brussels within the hour."

Produced by the Met Office, on behalf of the Maritime and Coastguard Agency, the shipping forecast is aired at 12.48am, 5.20am, 12.01pm and 5.54pm.

Friday's mishap is not the first time the Shipping Forecast has run aground.

In 2010, Radio 4 presenter Susan Powell read out a forecast which had already been given out 24 hours earlier.

"'Unfortunately our usual switch from BBC World Service, which is broadcast on Radio 4 overnight, didn't go as planned and was delayed by around 20 minutes," said a spokeswoman for BBC Radio 4. "We apologise for the inconvenience."

The explanation is surely going to be very simple - and far from being "a technical fault".

I'd bet that the Studio Manager responsible for putting out the Radio 4 programme simply hadn't taken 'Network' back from the overnight World Service feed.

He - or She - was undoubtedly doing the job of fading up the appropriate source (be that the Newsreader or the 'local' Con Announcer reading "the Ships") whilst listening to 'Desk Output' rather than the off-air/Check Receiver feed, and were thus unaware that their output was going nowhere, since they'd omitted the somewhat vital step of taking back control of the network from the Control Room.
I'd further venture that this human error was unfortunately compounded by those in Control Room (who oversee the network 'over night' whilst the World Service feed is switched to the R4 network, thus bypassing the unmanned Con suite) being distracted by some other incident and not realising that the network hadn't been taken back.

It's a crying shame that the 90-year-old record has not been meticulously maintained, but having done that Con job for several years myself (back in the day - or night shift!) I know that when you're 'very tired' or 'only just awake' it is all too easy to overlook something simple.
That poor SM will be haunted by their 'failure' for many a year to come - I doubt they'll be allowed to make the same mistake ever again!

There's probably no jackfield to put a "double-ender" in to bypass a duff computer either.
Dave

Many an SM would have probably faded up the wrong thing...as long as there was output they would have thought-"It's all right leaving here"