Hence the fact that large multi-pocketed combat trousers are more popular in inner cities than in Serbian war zones. Of course, walking around like an extra in Platoon allows men to avoid the conundrum of why they have resisted evolving into a handbag-carrying gender. While women have bags down to a minimalist art-form - the pinnacle of which can be described in one word: Prada - it's impossible to find such a precise definition for men.
Try flipping through the fashion pages of the current men's style mags for the ultimate (i.e. extremely expensive, sleek, and black) bag and you're likely to be disappointed. Not only are men's bags noticeable by their absence, you will not even see anything as bulky as an American Express card interfering with the cut of the cloth. Unless, that is, the model in question is dressed in the latest designer Arctic wear and knee- deep in a freezing stream, in which case an olive green rucksack is deemed acceptable.
Like the record bag before it - in which nobody really kept 12-inch records - here, form has little to do with function. It's unlikely, for instance, that you will see someone on the bus with an ice pick hanging from their Karrimor. They just want to express something more than "I am carrying my crap to work in a nice bag". Something along the lines of "I've got more balls (and toes) than Ranulph Fiennes", even if they've only ever spent one night sleeping under canvas, and that was roughing it at Glastonbury.
The posh boy's own ones - like Hackett's (0171-623 3133 for mail order) boxy pocketed A-frame-styled rucksack (pounds 195), or Barbour's gamekeeper- inspired Highland Thornproof waxed shoulder-bag (pounds 59, 0800 009988 for nearest stockist) - are not unlike those 4x4s you see sitting in Sainsbury's car parks. Yet even the sexier sports backpacks, worn casually on one arm (for optimum credibility now and maximum back pain later), are no less illusory. Although Eastpak and Jansport seem to have cornered the casual, nylon utility market, surf, climbing and skatewear labels like Mambo, Burton and O'Neill have also muscled on to the scene.
The most extreme example of outdoor gear as work bag is the Jann Inyan Deluxe Aquapack (pounds 75, 0131-467 6467), a red and black, three-tiered backpack which includes a 2-litre liquid container to prevent dehydration. Wearers think this implies that they enjoy speed hiking at the weekend. What it actually infers is that they are either a) alcoholics, or b) have a weak bladder. Although they are compact, lightweight, and bestow manliness on latter-day urban adventurers like so much cheap musk, the problem with backpacks is that they lack both gravitas for more formal occasions, and protective strength in those moments when they drop from overhead lockers on approach to Heathrow (bang goes the green-label Jack Daniel's).
Sadly, the older one gets, the more ominously the shadow of the leather attache case (and the conformity it imposes) looms on the horizon, like the Grim Reaper's first calling-card. Today, a friend I normally associate with gaudy sports holdalls (naff, unless containing dirty sock and shinpads) and Sunday-morning knockabouts, arrived at my office carrying a robust- looking case.
I was mortified. Partially I suspect because, of all the bags into which I've delved, the only one which seems both timelessly classic and effortlessly contemporary is also an attache case. Worse, it is metal, which instantly conjures up visions of media types trying to give the impression they are "creative" by lugging about those knobbly steel camera cases (no camera inside, of course).
The Zero Halliburton range (0181 280 3080 for stockists), however, is in a (flight) class of its own. The Kevlar of cases, they are constructed from "space shuttle aluminium" to withstand 50,000 pounds per square inch, have a water-resistant seal, and come with a lifetime's warranty (although judging from the pounding they can take, including terrorist explosions, it has more chance of surviving life-threatening situations than you do).
More importantly, if the biggest daily danger you face is the rush-hour crush, their unyielding bodywork makes for a good battering ram when you need to escape from the throng at Charing Cross. In the 60 years since they've been making them, the case's exterior design has only been slightly tweaked, with a discreet combination lock hidden under a flap, and two sets of running ridges down the sides providing the only relief on an otherwise sleek metallic finish (in satin silver, polished gold - more tasteful than it sounds - onyx, Arctic midnight and gun metal).
The insides, meanwhile, feature leather dividers on the topside for documents, and high-density foam padding to stop your sandwiches banging about too much (although special editions also have straps to hold down laptops and cameras in transit). The company does a whole range of luggage, but the satin silver, 5.5-inch-deep Presidential Attache (pounds 585) is probably the most versatile (wide enough to squeeze in a change of clothes and toothbrush, but not big enough to feel like bulky luggage). And the acid test for the Zero Halliburton? Stuff reckons it's the 32nd most important thing a man will ever need. But what do they know?
COOL CASUAL BAGS
n Snow 35, pounds 65, Karrimor (enquiries 01254 893133). The coolest outdoor bag around, the Karrimor Snow has a strap specifically to hold your snowboard (or a copy of The Independent), a mesh pocket for wet gear and a 35-litre capacity for your CDs, cab receipts and spare toothbrush.
n Nitro 24 Rucsac, pounds 65, Berghaus (enquiries 0191 415 0200). What, no "k" on the Berghaus typewriter? The best bag for comfort, the Nitro 24 is padded and ventilated to prevent nasty sweat patches, while the detachable black and white check flap can be removed and re-attached across the chest when carrying heavy loads (there's also a strap to spread load off the back).
n Shoulder bag, pounds 79, YMC (0171 729 2777). For those with a sense of fun, this bag is rather like a retro accessory from an episode of Space: 1999, its old school metal zippers sliding back to reveal a luminous yellow interior with clear plastic holders for credit cards etc.
n Backpack, pounds 70, Vexed Generation (after 17 November on 0171 287 6224). Basically, this is a record bag which straps to the back via a diagonal sash across the chest. It comes in two sizes - and daring colour combinations, including purple, yellow, red and the more subtle olive, black and brown - and it's guaranteed for three years.
What Real Men Have In Their Bags
Entertainment. The Panasonic (enquiries 0990 357357) L10 Portable DVD Player costs pounds 1,000 and is the essential executive toy this Christmas
A passport (UK Passport Agency 0990 210410) - real men can never be too prepared - expect the unexpected and you won't get caught out
Communication. Nokia's (0171 437 4380) 9000i mobile phone - pounds 250 with contract - is the heavyweight king of telecommunications, with an 8 megabyte brain. It's a phone, an electronic organiser, an alarm clock, a fax and e-mail machine, and a web-browser
Laptop. The Dell (01344 860456) Inspiron (pounds 2,583) has a 4Gb hard disk, a Pentium II processor, 65,000 colours and so on so now there's no excuse not to write that film script on the way to work
The essentials - a toothbrush, condoms, deodorant, a Swiss Army knife, pounds 1.74 in loose change, a pencil with broken lead, tickets to last week's Spurs game...