It has infuriated clumsy breakfast eaters and puzzled scientists for more than a century.

Now boffins from Manchester claim to have found an answer to age-old question – why does toast always lands butter side down?

Conventional wisdom would suggest buttered toast has a 50/50 chance of landing butter side down.

However a team from Manchester Metropolitan University (MMU) have debunked that, coming up with a new formula that explains why a dropping a piece of toast from the breakfast table always ends in a greasy mess.

Led by food science specialist Professor Chris Smith the team dropped 100 slices of toast from table height in a special lab experiment.

They discovered previous studies fail to take account in the physics of the bread itself.

Bread is made up of pockets of air which effect its drag as it falls.

Buttering one side of the bread changes this and means it only has the opportunity to rotate one and a half times.

As toast is always placed butter side up, it inevitably always lands butter side down. Professor Chris Smith said: “Our research shows that sod’s law really does exist when it comes to dropped toast

“The upshot is that if you want to ensure your toast lands butter side up then you should invest in a higher table of approximately 8 ft high that allows the toast to rotate a full 360 degrees.

“Failing that – try not to drop the toast!”

The issue was first raised as early as 1835 with an article in a New York magazine.

The research was commissioned to mark the launch of the latest series of The Big Bang Theory on DVD, a comedy about a group of socially awkward American scientists.

Prof Smith said: “The question of whether the toast does indeed always land buttered side down is exactly the kind of quandary that would keep the characters in Big Bang Theory awake at night.”