So they want 58 days. When you’re trying to sell something, always go with your highest price first. It’s the first principle of haggling. Who doubts they’ll settle for less?

Last week the Home Secretary claimed she didn’t have a clue how much they were going to ask. It didn’t take long for her to calculate her profit margins as it turned out - they saw last time that at 90 days demand was too elastic.

Now it’s a question of who bottles first, the government or those who don’t want to move beyond 28 days detention. If it’s the latter then we get into the horsetrading to see how far both parties are prepared to move.

Any number between 29 and 58 is a victory for the government. They get an increment and, like last time, get to smear their oppenents as appeasing suicide bombers. When it’s actually the other way around.

They can then come back next years and the next and the next to demand another increment. They’ll go with the highest price first, 72 days maybe. Under this process they’ll eventually get their way - and why stop at 90?

(See also Parkinson’s Law.)