This past few months I have been conducting an experiment on my colleagues and I hope you'll find the results useful.

It is the bugbear of any modern workplace, stopping people "borrowing" your milk from the office fridge leaving you nothing for your tea or coffee. And in the name of science I decided to do something about it. After all, science is the answer.

Fortunately the BBC has an Editorial Policy department to help me navigate any potential difficulties in conducting experiments that could directly impact the health of my co-workers. It was agreed as long as I didn't add anything harmful to my milk I could go ahead.

This meant of course that this would be a psychological experiment and I would have to rely on altering the physical appearance of bottles and the milk itself to deter light-fingered caffeine addicts. Other measures that were suggested such as using silver nitrate to chemically brand a thief were not allowed.

So with a bit of help from posters at the Bad Science forums and Bang Goes the Theory's Dr. Yan Wong I drew up a list of potential milk-modifications and testing got underway.

I kept things simple, leaving an unmarked control bottle of milk alongside the altered one. At the end of a week I compared one with the other to give a league table of the most effective ideas. So without further ado here are the results from five weeks of concentrated testing over the last year from worst to best deterrent;

In last place and so therefore the least effective modification was a bottle of milk with my boss's name on it which actually vanished completely from the fridge. Fourth a milk bottle with my name on it. Third place went to a bottle which I added some staring eyes to the label designed to trigger feelings of being watched in potential milk snatchers. In second place a bottle where I used food colouring and coloured the milk green. And the bottle that lost the least amount of milk to theft? One labelled "breast milk".

Now these are of course absolute measurements of the amount of milk liberated by my colleagues each week. It's possible that in any particular week the more morally ambiguous or caffeine-addicted members of staff might have been on holiday or not in the office that much. So that's where the control comes in.

We can compare how the control faired each week and use that to create a "fudge factor" in a fine scientific tradition. When we apply the fudge factor we get the same order for our experiment except the most effective carton-modifications are reversed with green milk coming out on top and breast milk slipping to second.

So what does this tell us? That a few drops of green food dye and writing "breast milk" in biro on the label of your carton will encourage most people to leave your milk alone.

But the most effective solution I found after more than a month of experimentation? Learn to like your coffee black.