Griffith Edwards, in his book 'Alcohol, the ambiguous molecule' (now republished as 'Alcohol: the world's favourite drug') cites a number of possible factors:

Alcohol as a pharmacological inhibitor

The explanation of alcohol-affected behaviour as the suppression of "higher", inhibitory brain functions fails to explain why drunken behaviour varies between individuals and across cultures..  "There seems to be more of metaphor than of brain science in this kind of theory." says Griffiths.

Some people, in some societies, may indeed behave in an aggressive or promiscuous manner when drunk, but the range of behavioural outcomes also includes calmness, joviality, passivity, indolence, affability, tolerance, sociability, generosity, volubility, confidence, loquaciousness, sentimentality, gaiety, euphoria, animation, tenderness, tranquillity, boastfulness, jocularity, silliness, laziness, effusiveness, vivacity, cheerfulness, relaxation, drowsiness, peacefulness, etc. In global terms, the most frequently emphasised outcomes are relaxation and sociability.

http://www.sirc.org/publik/drinking4.html

Drunkenness and temperament

Nashe's menagerie is an early version of the folk wisdom that in vino veritas, ie, that alcohol loosens the inhibitions and reveals something about the nature of the person beneath.  Who, for instance, is convinced that
alcohol can create anti-Semitism?

The immediate context

 An aggressive atmosphere is, unsurprisingly, more likely to lead to aggression.

Drunkenness shaped by culture

The early racist stereotypes of inferior races running amok on firewater weren't seriously challenged until a major anthropological study by MacAndrew and Edgerton at the end of the 1960's.  But the study did find that there are indeed major cultural differences not just in the rituals surrounding alcohol, but in the effect that alcohol has on behaviour:

MacAndrew and Edgerton, and subsequent researchers (Marshall, 1976; Douglas, 1987; McDonald, 1994; etc.), have provided overwhelming evidence...to illustrate the learning process summarised in Drunken Comportment:
"Over the course of socialisation, people learn about drunkenness what their society `knows' about drunkenness; and, accepting and acting upon the understandings thus imparted to them, they become the living confirmation of their society's teachings.
http://www.sirc.org/publik/drinking4.html

Heath (1998) provides the following clear summary of the ethnographic and psychological findings:
"There is overwhelming historical and cross-cultural evidence that people learn not only how to drink but how to be affected by drink through a process of socialisation...Numerous experiments conducted under strictly controlled conditions (double-blind, with placebos) on a wide range of subjects and in different cultures have demonstrated that both mood and actions are affected far more by what people think they have drunk than by what they have actually drunk...In simple terms, this means that people who expect drinking to result in violence become aggressive; those who expect it to make them feel sexy become amorous; those who view it as disinhibiting are demonstrative. If behaviour reflects expectations, then a society gets the drunks it deserves."
http://www.sirc.org/publik/drinking4.html

So is the British government,
in asking the drinks industry to clean up its act and with its avowed preference for a café culture, inadvertently contributing to the problem by strengthening the meme that associates alcohol consumption in young people with bingeing and/or violence?

Another possible contributing factor is that associating alcohol with unsocial behaviour makes it just a short step from I-did-it-while-drunk to Alcohol-made-me-do-it to I-am-not-responsible:

Expectations not only shape drunken behaviour, they also enable subsequent rationalisation, justification and excuses (MacAndrew and Edgerton, 1969; Gusfield, 1987). In cultures where there is an expectation that alcohol will lead to aggression, for example, people appeal to the fact that they were drunk in order to excuse their belligerent conduct. This is particularly evident in Britain, where defendants in court often plead for mitigation on the basis that they were intoxicated at the time of the offence. Perhaps surprisingly, British courts often accept such pleading, arguing that the behaviour was `out of character' - a standard metaphor for disinhibition.  In more informal social contexts, excuses such as "it was the drink talking" are even more likely to be accepted.
In cultures where learned expectations about the effects of alcohol are very different from the British, appeals to drunkenness as an excuse for aggressive behaviour would not only fail to be persuasive, they might actually compound the severity of the offence. Among Italian youth, for example, attempts to excuse violent or anti-social behaviour on the grounds that the person was drunk would meet with incredulity (Marsh and Fox, 1992).
http://www.sirc.org/publik/drinking4.html

Is the British disease contagious?

The association of alcohol with binge drinking and violence is spreading.  Possibly fuelled by Europe-wide comment on the British experience, there is evidence that young drinkers across Europe are developing a British attitude to drink:

Spanish Health Minister Elena Salgado says that the number of hospitalizations from alcohol abuse has doubled in a decade....In Germany, young people are drinking almost 30% more alcohol than four years ago. Emergency-room visits caused by "coma drinking" rose 26% between 2000 and 2002; half the patients were female. In Poland, where the number of adolescents who drink jumped 40% between 1995 and 2003, 20% of 17-year-old boys say they got in a booze-fueled fight in the last year. Eight percent of Swedish 15- to 16-year-old girls say drink led to unplanned sex, while 12% say it made them forget to use a condom.
Time Europe