One day, young Sarah girl was watching her mother make a roast sirloin of beef. She cut off the ends, wrapped it in string, seasoned it and set it in the roasting dish.

Sarah politely asked her mum why she cut off the ends of the roast. Mum replied, after some thought, that it was the way that her mother had done it.

That night grandma came to dinner and Sarah and her mother asked why she had cut the end off of the roast before cooking. After some thought grandma replied, she cooked the meat the way her mother had done it.

Now great-grandma was quite old and lived in a residential nursing home, so Sarah, her mum and grandma went to visit her and again asked the very same question.

Great-grandma looked at them a bit surprised and said, 'So it would fit in the roasting dish, of course.'