Roughly half of Ogilvy's rule book survives the AI shift unchanged. Roughly a third inverts. The remaining sixth no longer applies.
Survives: the supremacy of the brand, the discipline of testing, the primacy of the customer, the obligation of honesty.
Inverts: 'never write more than 12 words in a headline'; 'long copy outsells short copy'; 'show the product'. Under AI-mediated discovery and infinite-variant testing, the new answer is often the opposite — and provably so.
The most Ogilvy thing a 2026 UK marketer can do is to read the rules with respect, test them ruthlessly against the new medium, keep what holds, and rewrite the rest.