Best Case or Worst Case? Reading the Small Print on Official Timelines

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Recently I saw a well-known account share the BBC’s Black Sky headline with three words: “it gets dark.” Well, yes. But that isn’t the half of it.

When an official says how long something will take to fix, the first question isn’t “is that true?” It’s “what does that assume?”

Every estimate has a scenario behind it

Any timeline for getting something back, whether it’s the power, the water or full shelves, is built on a picture of what went wrong. Planners have to pick one. Often they pick the one they can plan for in detail, and that’s usually the tidy one.

That isn’t lying. It’s how planning works. The trouble is that the headline number travels on its own, and the scenario behind it gets left behind. By the time it reaches you, “five days if nothing is broken” has become “five days”.

Questions to ask of any official timeline

  1. What scenario is it for? A clean shutdown, a storm, an attack? Switching something back on is a very different job from repairing something that’s broken.
  2. Who said it, and where? A published plan, a named official, or “a source”?
  3. Is it a target or a forecast? “Must be able to” is a goal for the system. It isn’t a promise about your street.
  4. Average, or everyone? “60% back within a day” also means 40% not. Somebody is last, and it could be you.
  5. What does it depend on? Fuel, staff, phones, spare parts, clear roads. Ask what happens if one of those is missing too.
  6. What does the same body say elsewhere? Official documents often carry the caveat the headline drops. Look for phrases like “depending on” and “reasonable worst case”.
  7. What would I do if it took twice as long? For your own planning, this is the one that matters.

Worked example: how long until the power comes back?

On 7 November 2026 the BBC set out its “Black Sky” plan for keeping FM radio on air during a long, national power cut. The emergency studio would be stocked for about three days. According to the report, planners first looked at five to seven days, then cut it after advice from NESO, the National Energy System Operator, that power would probably be back in two or three.

Here’s what twenty minutes of checking turned up.

  • Who said “two to three days”? An unnamed insider, quoted by the BBC. We couldn’t find a NESO publication that gives that figure. Reported, not confirmed.
  • What’s the official target? NESO’s Electricity System Restoration Standard. By 31 December 2026 it must be able to restore 60% of demand in each region within 24 hours, and all of Great Britain within five days. That’s a capability it must have, not a measured result. Britain has never had a total national shutdown, so it has never been tested for real.
  • Can they hit it yet? NESO’s own latest published assessment, for 2024, puts the average time to get 60% of the country’s demand back at 32 hours. That’s eight hours over the 24-hour target. And that figure comes from a computer model, not a real test.
  • What scenario is it built on? This is the part almost nobody mentions. NESO’s own paperwork for the standard says it is set against a system “in an intact and operable state”, with no significant damage to equipment. In other words, the grid has switched off, but nothing is broken. That’s the best case.
  • What if things are broken? The government’s own National Risk Register covers that. Its worst case for a cyber attack that brings down the grid says full restoration could take up to seven days. But it adds that, depending on the cause and the damage, getting critical services back may take several months. The caveat is right there in the official document. It just doesn’t make the headlines.
  • Why would damage take so long? The big transformers that step electricity up and down are built to order. Industry surveys in 2025 put the wait for a new large one at around two and a half years. Those are US figures, but Britain buys from the same world market. Unless a spare is already held, a wrecked transformer can’t be swapped out in a week.
  • What does damage look like in real life? The BBC article opens with an example. In December 2015 the River Lune flooded and knocked out the electricity supply to 61,500 people in Lancaster for several days. Some water supplies failed because they relied on electric pumps. The railway station, petrol stations and shops closed, most cash machines stopped working and the traffic lights went out. That was one city, and the rest of the country was still working and able to help.
  • What else does the plan lean on? In Lancaster, the two things that kept working were copper landlines and FM radio. The copper landline network is due to be switched off on 31 January 2027, and the future of FM radio is under government review. Roger Kemp, the engineer who studied what went wrong in Lancaster, was asked whether things have improved since. His answer: “If anything, we’ve gone backwards.”

So three numbers are floating about:

Figure Who says it What it assumes
2 to 3 days Unnamed source, via the BBC Not stated
5 days (60% of each region in 24 hours) NESO’s legal target from 31 Dec 2026 Grid switched off, nothing badly damaged
Several months for critical services National Risk Register, cyber attack scenario Depends on the cause and the damage

None of them is wrong. They answer different questions. Planning for the clean case is fine. But a best-case plan needs a worst-case plan beside it, and everything the government has made public stops at about a week. Programme Yarrow, the national blackout plan leaked in 2022, covers outages of up to seven days. The BBC’s studio is stocked for three. The Risk Register names several months, but we couldn’t find any published plan for coping with that.

Most power cuts are local and short, and this isn’t about expecting the worst. It’s about knowing which case a number covers. The government’s Be Ready advice is three days of supplies. Treat that as the floor, not the ceiling. If you can stretch to a week, do, and spend ten minutes thinking about what you’d do if a long cut went on past that.

How I do it

When someone gives me a number, the first thing I want to know is what they’re assuming. My brain is always looking for the weak spot: the one thing that, if it fails, takes everything else down with it. Official plans are usually built around the tidy version, because it’s the one you can plan in detail. That’s fine, as long as everyone knows that’s what it is.

The NESO figures are a good example. Getting the power back in a few days assumes a pretty clean shutdown, with nothing badly damaged. That’s the best case. If you only plan for the best case, you’ve planned for the day you didn’t need a plan.

Planning for the clean case is fine. But if you plan for the best case, you have to plan for the worst one too. Computer models don’t beat real life. They’re written by people, and people often aren’t so much interested in seeing what happens as in reaching the answer they started with. Without a plan for both, the official line feels like “pat pat, there there”. I don’t think the UK has a longer term plan.

On the island, we knew what winds over 100mph looked like, so we were ready for them. Where I live now, most people have never seen that, and they’ve no picture in their heads of the damage it can do. That’s the real gap. If you’ve never seen the bad version, you don’t think to plan for it. Reading the small print is one way of borrowing that picture from people who have.

Checklist

  • Next time you see an official timeline, find the scenario behind it
  • Ask whether it’s a target or a forecast, and who actually said it
  • Look for the caveat in the original document: “depending on”, “reasonable worst case”
  • When you see a percentage, think about the people in the rest of it
  • Plan for twice as long as the headline number
  • Treat the three-day Be Ready advice as a starting point, not the finish line

Sources

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