I did indeed pay for it later. We met a friend at the Hendon Air Force museum, in which The boys totally ignored the planes, and just raced around the acres of carpeted space. Which was fine. Then in the children's interactive bit, he had a total meltdown because another boy was pressing a button he wanted, and I had to physically drag him away. At which point he screamed at me to get my hands off him, that he really really hated me, and that he was going away now to get lost.
He did however then ask for a cuddle, and say 'I can't control myself when I feel sad as I haven't got a switch.'
And yesterday said: "there's a windows iPad that runs Mozilla Firefox, Google chrome, internet explorer and safari. I just saw it on a bus advert." He's Four.