I am looking forward to stretching my legs. One of the good things about Heathrow is that they insist on you walking miles to passport control and baggage collection after a flight. Strangely, I find this walk one of the most enjoyable parts of any journey involving a flight. It allows me to people-watch at my leisure, as the plane empties and everyone makes their own distinctive way to customs and the baggage hall.

It is like some bizarre unspoken race and reminds me of a comedy sketch I watched years ago about a race commentary for a random group of morning commuters over Waterloo Bridge in London. Not that they knew they were racing. In a way, people at airports are slightly different, as some definitely believe there is a race to be the first to get through customs and meet their relatives in Arrivals. You see it when they weave and wend their way past others, pushing their partners on. You see it in their faces when their luggage comes off the carousel first. They boldly wear the grin of victory, head held high, as they wheel their trolley past the rest of us mere mortals, who are still waiting.

    As I amble off the plane, the race begins and a few fall at the first hurdle. This is invariably someone who insists on re-packing their hand luggage halfway along the narrow gangway. It is here that polite racers lose valuable time and the more aggressive competitors gain an early advantage. The latter vault the innocent soul oblivious to the chaos behind him or her and speedwalk into the arrival lounge. Some of the passengers closest to the offender bend down to help speed the process of luggage reorganisation. This rarely helps for there is always one bottle of duty-free that doesn't fit anywhere or a catch that doesn't fasten and the process must begin all over again.

    By now, even the most patient of passengers looks exasperated and a few cough and hem to hurry the person along. He or she at last notices the stoppage behind and moves as far over to one side of the gangway as possible. The passengers trickle past, the false start is over and the race begins in earnest. Some, frustrated by the initial hold-up trot off around the corner and into the arrival lounge, duty-free clinking ominously as they run. The less practised of these drop belongings and suffer a ten-second penalty as they retrieve their fallen items.

    Once out of the arrival lounge, the racers' different styles and techniques become more apparent. Far ahead in the distance are the sleek hares of the race, striding along the moving walkway, carrying the lightest of hand-luggage, unburdened by duty free, magazines or water bottles. All unnecessary ballast has been shed in the plane or at the nearest bin in the arrival lounge.

    There is a small harried group of passengers who jog then walk then trot, anxious that the delay in landing will cause them to miss their connecting flights. They carry twice or three times the legal limit for hand luggage and have shopped freely on board. As a result, they now have a collection of plastic bags tied to a temperamental trolley that runs on one wheel and is causing those overtaking it to veer suddenly whenever it lurches towards them and bangs into their legs.

    Next come the families, each child with their own bag that drags and bangs and bounces along the moving walkway. Father ambles on ahead of them, passports and tickets in hand, oblivious to the children's whining demands for sweets, a drink, the toilet, someone to carry their bag, someone to carry them for a while. Behind them trots the mother, hair flying in all directions but that intended, skirt stained with blackcurrant juice, two bags, one on each shoulder, a handbag fallen down over one arm, clutching soft toys and drinks cartons the children have dropped or discarded. Before the end of the walkway, she holds the children's two bags as well and staggers along, watching them race to catch up with their father, who waits impatiently at the next moving walkway.

    Weaving in and out of the families are lone travellers in dark suits and court or patent leather shoes. Their white shirts or blouses are creased more than usual for a workday but their hair is combed and their faces glisten with freshening spritzer, as recommended in the latest magazines. Their teeth shine in the intermittent flourescent lighting, as they breathe mint freshness from their travel toothpaste into the air. They travel like cabin crew with one neat long-handled attache case on wheels, fawn overcoats draped neatly over their arms. They manoeuvre their trolleys expertly around and among the legs and bags of the other passengers. They are late starters but in with a chance of winning the race if they keep the same steady pace. They will certainly beat most of the families, who fall away at the first drinks machine or toilet.

    A small band of student travellers form bottlenecks at points along the moving walkway: they walk five or ten paces, stop and ride a while, and start to walk again just as you draw level with them and are in sight of overtaking. They pull away with their lazy, leisurely gait and leave you standing in the way of everyone behind.

    I hear the tuts and feel the push forward behind me and know that Mr Last Minute is coming up fast on the outside. He is the one who sits in the plane at the front and waits while everyone else to get off. Once he has the plane to himself, he slowly collects his belongings from the overhead locker and anything else that interests him from the debris on the seats between him and the exit. He tucks his prizes into his bulky shoulder bag and concentrates on catching up with and passing everyone. He apologizes constantly and, when he reaches my group of racers, he has it down to an abrupt but loud “Sorr', Sorr'”. He pushes at your shoulder until you give way and step aside for him to pass. As he comes alongside, his shoulder bag swings and bruises your arm, leaving you holding it, standing looking mournfully at his back, losing valuable time and ground. I usually mutter something indignant, although not anything he can hear, he is long gone. I fall back into stride and rejoin the field.

    Coming down off the sloping walkway, the racers tumble out into customs and are momentarily thrown off balance. We catch sight of the desks at the end of the hall and sense the finish line is in reach. The roped tracks incentivise us and we rally one last time, sprinting now, holding out our passports in front of us, in case it is a photo finish. The winners preen themselves and pat down their clothes, as they are waved through customs. For the losers, there is the consolation that their bags may well appear first and they will win the second stage of the race.