Why are there two high tides each day?

Dear Naked Scientist!

I live in Jersey, Channel Islands, where we have some of the highest tides in the world. Sometimes 12 metres on a spring tide.
I can understand the reasons for the tides; the influences of the sun and the moon but one thing that has escaped me is why there are 2 high tides (and obviously 2 low) every 24 hours.
Every point on earth spins round the earth axis once in 24 hours so why is there a 'bulge' on the far side as well as the side towards the moon/sun?

Best regards

Ola Gabrielsson
Jersey