And worried chaps who hide their shrivelled wangers in a quiet corner of the communal showers may be relieved to learn that your everyday love muscle apparently checks in at a relatively modest-sounding 5.16 inches (13.12cm) long when erect, while boasting a circumference of 4.6 inches (11.66cm).

In its flaccid state the average one-eyed trouser snake shrinks to 3.6 inches (9.16cm) in length, and has a girth of 3.7 inches (9.31cm).

The study – published in the BJU International journal of urology – is the first to combine all existing data on penis length and girth. The participants were men aged 17 to 91 who had had their penises measured in 20 previously unpublished studies conducted in Europe, Asia, Africa and the United States.

The team found no evidence for differences in penis size linked to race, but admitted that a full comparison could not be made as most of the participants were of European and Middle Eastern descent. Neither did they find any convincing correlation between a man’s shoe size and the length of his joystick.

The collated figures have been used to devise a graph for doctors to use in counselling men with ‘small penis anxiety’. Some men become so hung up about not being well-hung that they are diagnosed with body dysmorphic disorder – a debilitating psychological condition that can lead to depression and even suicide.

The survey found that in reality only 2.28 per cent of the male population have an abnormally small penis – a similar percentage to those who boast an unusually large chopper in the ‘Long Dong Silver’ porn star league.

Lead author Dr David Veale, from the Institute of Psychiatry, Psychology and Neuroscience, King’s College London, and London and Maudsley NHS Foundation Trust, told the Daily Mail: “Men compare themselves in locker rooms and with pornography on the internet and believe they are inferior. Some men have been teased by sexual partners about their length. There are lots of men who might be worried – and we think reassuring men they are in the normal range will help.”

Meanwhile there is no truth in rumours that B&Q have been experiencing a run on tape measures.