Every established discipline has a severity classification. Seismology has the Mercalli Scale. Meteorology has the Beaufort Scale. Nuclear safety has the INES. Each one works the same way: observable effects at each level, no instrumentation required.

Programme management has no equivalent classification for the things people say when a programme is not going to plan. We have RAG statuses. We have earned value. We have gateway reviews. None of them capture the specific texture of the moment when someone says ‘the requirements changed’ as if that explains why the programme is twelve months late and thirty percent over budget.

After twenty years of sitting in programme reviews across guided weapons, naval platforms, and critical national infrastructure, I started noticing that the excuses are not random. They cluster. They have properties. Some are inert — technically true but explaining nothing. Some are volatile — reacting explosively when placed next to data. Some bond to everything. Some change depending on the audience.

It occurred to me, somewhere around year fifteen, that this is chemistry.

The Periodic Table of Programme Excuses organises the most commonly observed excuses by their chemical behaviour. Each element has a symbol, an atomic number, and an atomic weight representing the damage it does to the programme when deployed. The elements are grouped into eight families, each defined by how the excuse behaves when it encounters evidence, challenge, or the passage of time.

The element groups

Noble gases

Technically true. Explain nothing. Do not react with evidence, challenge, or solutions. Noble gas excuses can persist in a risk register for years without decaying. Their defining property is inertness: they describe a situation without advancing it. ‘The requirements changed’ is the hydrogen of the table — simple, abundant, and completely inert when examined.

Alkali metals

React violently when exposed to data. These are the excuses that cannot survive contact with the programme’s own metrics. Place an alkali metal excuse next to the EVM, the schedule, or the cost report, and the room gets hotter. ‘The funding profile doesn’t match the delivery plan’ is explosive when followed by: ‘Did you raise this when the funding profile was set?’

Halogens

Bond to everything. Universal excuses applicable to any programme, any problem, any domain. Their power is in their generality — because they are always partially true, they cannot be fully refuted. ‘It’s a resource issue’ bonds to schedule, cost, technical, and commercial problems simultaneously. Breaking the bond requires specificity: is it a skills issue, a headcount issue, a retention issue, or a prioritisation issue?

Transition metals

Change depending on the audience. Multiple oxidation states. The same excuse is presented differently to the customer, the board, and the team. The underlying chemistry is identical. The presentation adapts to the environment. ‘The legacy system is harder to integrate than expected’ is an unforeseen technical challenge to the customer, a manageable risk to the board, and something the engineering team flagged at PDR.

Alkaline earth metals

Heavy. Stable. Hard to shift once deployed. These excuses describe genuine structural constraints — procurement timelines, security clearance, contractual dependencies — that are real, immovable, and were foreseeable at programme initiation. Their damage comes not from being false but from being treated as unforeseen when they were entirely predictable.

Metalloids

Part truth, part excuse. Structurally ambiguous. ‘We were probably too optimistic at the bid stage’ can be a genuine insight or a retrospective shield, and it is often impossible to tell which — including for the person saying it. Metalloids sit on the border between honest assessment and defensive positioning.

Lanthanides

Rare earths. Only appear on programmes above Clusterfuck Level 7 and above £500M. Irrefutable, unverifiable, and politically protected. ‘The Minister changed the priority’ invokes a force that cannot be challenged in the room where it is deployed. The audience must accept it on faith. Lanthanides include AUKUS, Five Eyes, Integrated Review, and SRO changes — the excuses that operate at the intersection of programme management and geopolitics.

Actinides

Radioactive. Toxic. Long half-life. These are the excuses that contaminate everything they touch. They do not merely explain a problem — they prevent the problem from being discussed, investigated, or resolved. ‘Lessons will be learned’ is the most toxic element in the table. Half-life: infinite. No lesson identified by this phrase has ever been applied to a subsequent programme.

How to use this table

Sit in your next programme review. Listen. You will hear at least three of these elements within the first hour. The value of the table is not in identifying the excuses — you already know them. The value is in classifying them, because the classification tells you what to do next.

When you hear a noble gas: acknowledge it and move on. It is true and useless. Do not spend meeting time discussing it. The requirements did change. The question is what the programme is doing about it.

When you hear an alkali metal: apply data. The reaction will be violent but diagnostic. If the excuse survives contact with the EVM, it might be valid. If it does not, the EVM has just done the most useful thing it has done all month.

When you hear a halogen: break the bond. ‘It’s a resource issue’ is too general to act on. Force specificity. Each specific version of the excuse has a different solution. The halogen is preventing you from reaching it.

When you hear a transition metal: ask the same question to a different audience. If the excuse changes oxidation state, the chemistry is doing the work. The adaptation is the information.

When you hear an alkaline earth metal: ask when it was first identified. If the answer is ‘at programme initiation’, the excuse is valid but the governance that failed to plan for a known constraint is the actual subject of the conversation.

When you hear a lanthanide: you are on a programme that has moved from a technical problem to a political one. The governance response changes accordingly. Lanthanides cannot be challenged with data. They can only be absorbed into the plan.

When you hear an actinide: leave the room and write down exactly what was said. Actinides prevent governance from functioning. ‘Lessons will be learned’ means they will not. ‘That’s commercially sensitive’ means the commercial position would change if the information were known. ‘This is not a blame exercise’ means it is. The actinide tells you what is really happening by telling you what cannot be discussed.

The three extended rows at the bottom of the table — Agile Ceremonies, Assurance Theatre, and Governance Frameworks — are the excuses that live inside the processes designed to prevent excuses from being necessary. They are the governance system’s immune response turned against itself.

The table is not finished. It will never be finished. Every programme generates new elements, and some of the most interesting specimens have not yet been classified. If you have discovered one that is not in the table, the contact page is the right place to submit it for analysis.