The Information Commissioner’s Office operates on legal realities, i.e. “What is currently the case?”. This explains why the ICO may enforce at one minute past midnight on the day a programme comes into force, but not before. It can be infuriating, but that is what a regulator is empowered to do.

“Being legal” is a binary state – something is either legal or it isn’t.

If there is one way in which a situation or scheme or system is legal, and no ways in which it is illegal, even if there are many ways in which it is really creepy, it’s still legal. This is often infuriating in the private sector, but in the public sector there is a very different environment – because, most of the time, public sector bodies don’t get to operate in ‘stealth mode’. In the private sector, the ICO by and large regulates against dishonesty rather than for good data hygiene. The public sector is held to a higher standard.

Either way, before 00:01 on the first day of operation, the ICO operates only on scenarios, or possibilities.

You can in fact put a scenario to the ICO and, while its officials don’t necessarily like hypotheticals, they will offer an opinion based on what you have said.

What most people fail to understand is that ICO decisions are based exclusively upon the scenario (or evidence) as presented to it.

If you tell the ICO that you will do X, and its officials suggest that X is most likely legal, then that opinion will simply not apply if at 9:12 am on the second Thursday of the following month it turns out you instead do X plus Y; that is a different scenario.

Clearly, if you miss out critical information from the scenarios you present, then the ICO’s opinion cannot and does not reflect what you are actually doing; it only reflects what you say you are doing. Remember, the ICO operates on reality – which is why it can only enforce at 00:01 on the first day of operation.

Where the ICO issues “contradictory advice”, it is almost always because the information it was presented with changed.

In a hypothetical scenario, when the scenario changes, the ICO reserves the right to change its mind. What else would it do?

If ICO officials “change their minds” when presented with what is ostensibly “the same” information, it likely demonstrates the fact that – in the ICO’s opinion – material information was omitted the first time.

For example, care.data’s communications programme collapsed because what NHS England told the ICO turned out to be incomplete – when other information was added, and checked against reality, what NHS England said it would do, and what it actually did, were shown to be materially different.

If you want to understand why the ICO changes its mind, the best place to start is with what you didn’t tell its officials, that someone else did.