GIVERS whose efforts at wrapping leave their Christmas presents looking like an origami car crash will find solace today - scientists have come up with a mathematical formula for the perfect wrap.

Online retailer Amazon warned today of a sales slowdown in the run-up to Christmas as it turned the screw on high-street rivals in the UK by cutting delivery costs.

Online retailer Amazon said today that the latest instalment in the adventures of schoolboy wizard Harry Potter had smashed all its records for deliveries.