Happy-Christmas formula revealed

A maths expert has calculated the perfect ingredients for a happy Christmas.

The formula is:

- Three weeks off work;

- 7,000 calories;

- 15 centimetres of snow;

- No more than 10 hours shopping.

Chris Green, who is a maths teacher, carried out the research for Oxfam to promote the charity's 'Unwrapped' scheme which supports poor communities around the world.