There is a good reason why Italy has managed to resist the globalisation and homogenisation of food better than other European countries, and that is the Italians firm conviction that whatever is produced locally is better than what is produced anywhere else.

This applies particularly to olive oil; every Italian region with olive trees claims to produce the best, with Tuscany being especially successful in promoting its oil, selling it in very small, very elegant designer bottles at very handsome prices. Lazio is a poor sister, and indeed much of the oil produced in the plain is not exceptional; but what comes from the hills, which are sometimes vertiginously steep and at heights that are at the upper limits of survival for the trees (600-700 m above sea level), is nectar.

Where can you get it? Not in commerce and probably not even at the local mill such as the one described below, where they sometimes crush olives from Puglia and sell the oil as local. Either you have to produce it yourself or else you must know an honest supplier with a surplus.

The season is short but very intense; the variables, chiefly the weather and the temperamental machinery in the mill, are indeed very variable. Olives should be milled within a week at most after being harvested, and as soon as the sun comes out in this period everyone starts picking because tomorrow it could start raining.

Harvesting starts on about 10 November, entailing first the assembling of the equipment; this includes large nets to spread on the ground, little plastic rakes, known as mani, which are attached to long bamboos, and a pruning saw to remove crossing or excessively strongly growing upright branches. Having spread the nets carefully so as to avoid those gaps, which the olives have an extraordinary talent for finding, most of the party rakes away overhead, combing through the twigs with the mani to dislodge the olives, while someone in the tree rakes higher up and saws off what needs pruning. When there are no olives left the nets are carefully rolled up, the contents (olives, leaves and twigs) transferred into boxes and its on to the next tree.

This is all much harder work than it sounds, as those neat little trees you see in the distance, set on steep slopes, are actually much taller than you think, and the effort of raking away with a long pole three or four metres above your head is considerable, to say nothing of the dangers for whoever is up the tree. The local hospitals emergency section works full time in this period.

The olives gathered in this way must now be cleaned. Commercially this is done with strong currents of air to blow out the leaves, and water which floats away the twigs, but these systems do not remove all the debris. Small-scale growers, on the other hand, use a crivello, an ingenious device consisting of a wooden frame, 1.5 m long and 75 cm wide, holding a layer of thin, parallel metal rods, over which the olives roll and through which twigs and leaves drop. It is remarkably efficient, and proper cleaning is one of the secrets for having the best oil, as crushed twigs and leaves spoil the flavour.

Having cleaned the crop from the 33 trees in our own gardens, we set off for the village mill, misleadingly named Frantoio Oleificio Moderno. Decidedly not very moderno here, which is a great part of its appeal. We have had a booking here for some two weeks but this does not mean a great deal. In spite of the bookings, long queues form from 06.00. We unload the precious boxes at 06.30 and join the queue, but are by no means first and have no certain knowledge of when we will be out. There is considerable camaraderie; olives are inspected and complimented on, even though everyone knows perfectly well that theirs are the finest, but progress is agonisingly slow; the delicious smell of fresh oil permeates the air, and the whole place shines with its gloss. The proprietor, concentrating his whole annual turnover into six weeks, is red in the face with fatigue. He combats this with cigarettes and innumerable caff corretti; he is not always coherent but is dependably foul-tempered. The people in the queue dont mind that, however, as they are grateful that anyone is prepared to do such a tiring job.

Finally, in the early afternoon it is our turn, and we tip the olives into the great molazza, a steel basin some three metres across; the two huge wheels of Sardinian granite, each weighing some 2.5 tons, set on their side and attached to a central axle, slowly start to revolve, and in a quarter of an hour reduce the olives to a purplish-grey pulp. Until very recently this used to be spread on hemp mats, which were piled on top of each other and then squeezed in a great open press, and you could watch the oil ooze out and collect at the bottom, a technique unchanged since ancient Roman times. However, Brussels has interfered; hemp mats have been deemed unhygienic, which perhaps they were (did it really matter?), and the pulp is passed for pressing in a gleaming piece of stainless steel a touch of moderno here, but not very picturesque and then on through a maze of pipes running over the floor to the centrifuge, where the oil is separated from the water contained in the olives.

At this point everyone gathers round, as the first oil appears at the end of a long spout, trembles and finally flows in a thin, steady stream into the glass demijohn below. They dip their finger in, taste, declare it exquisite, secretly sure that their own will be better; off we go past the envious, ever-lengthening and ever less good-humoured queue.

Ours is definitely the best.