it's interesting just how many people close to her are mentioning her wicked sense of humour. On this I remember two incidents:
At one of the big showpiece events for the Silver Jubilee, the person managing was Michael Parker - one of his rules for these events was 'if it's not too complex and risky then you're not on the right track' - and just as things were going a bit pear shaped he said to the Queen '...ma'am it's all going terribly wrong....' to which she said '...is it?....excellent!!....'
And then at Balmoral, in her trademark Landrover with a security guy next to her, stopping up in the hills next to a person walking, who then said '....have you bumped into the Queen...' to which she replied, pointing to the security officer '....No, but he has....'