Ah, Knoydart! That remote peninsular is reached by no road, but by a long ride up the West Highland Railway and Bruce Watt's boat out of Mallaig. Leap onto the jetty at Inverie with a real feeling of anxiety and self-reliance. The boat won't be back for two days, and it's thirty miles to the bus stop.
And those miles aren't easy ones. Knoydart's rough bounds are well separated from the so-called Real World, concealed in mists and snowclouds, defended by midges and the mysteries of the ferry timetable. Here the sea creeps deep into the hills, the hills drop steep into the sea - and 8ft of water a year are transferred from the one to the other.
Knoydart in the rain is where Hamish Brown came closest to abandoning his All-the-Munros walk. Get lost in the mist and it's 600m down a vertical bog, and what you get at the bottom is a river in spate and no footbridge.
It's best, here, to expect anything at all in the way of weather. And when a surprising sun beat down out of a sky of blue - as it does not infrequently at all in the month of May - we were equipped to cope. In my sack was a small green Gore-tex bag supplied by an elderly but very lively member of the SMC. In Oliver's sack was a similar, and in his head the route-plan for this very eventuality.
Sgurr na Ciche. It's the hard heart of the Rough Bounds. Its rocky sides steepen as they go up, till its top contour-lines crowd so close there isn't even space for a spot-height. By the side of Loch Nevis we stopped to brew a simple supper, and looked at the Ciche. Its western ridge started as a seaweedy spine rising out of the loch; indeed, its rocky outline could be seen plunging on downwards into the salt waters. Sun-heat beat back at us off the rock-spine, the warm air carried the aroma of the bog-myrtle, and the bees were buzzing around in the heather. Assuredly not a night for the bothy.
And so we raced the setting sun up the three miles (and one vertical kilometre) of the ridge. All the way the pointed summit stood like a beckoning finger against the sky. We scrambled on hands and knees up the final steep metres to reach the cairn in time for the last two minutes of the day. The sun went down behind the rim of Ladhar Bheinn like an egg-yolk falling into the blades of a liquidiser.
At this point we may calculate the altitude of Heaven as 1042m (3418ft). For on Ciche's summit, at sunset, it is within touching distance.
Two minutes down the eastern sides we found, among all the bare schist, a grassy shelf sheltered by lumps of crag. Twenty miles away Nevis, that urban hill, crouched under the stars. All night long our noses poked into the night and were cooled and freshened by the breezes.
But by dawn those noses were damp ones. Grey rain had rolled in off the Atlantic. Tendrils of cloud swirled around our little hollow; we were annoying damp tealeaves to be scoured out of its pristine sink. We bundled up the bags and dropped 800ft to warm up before breakfasting huddled under a wet stone wall.
Julian Miles calculates that he's made about 8000 bivvy bags over the years, not to mention the more expensive but perfectly serviceable products of his competitors. Where are they all?
Is it just that the bivvy is so discreet that we don't see it? A gentleman who didn't give his name spent four months in his one, watching a farmhouse in Kent were some thieves were preparing to steal the great De Beers diamond from the Millennium Dome.
But are the other half-million or so bivvybags manufactured by Britain's lively outdoor suppliers - are all of them simply sitting in attics and their nervous owners taking them out every six months or so and saying do I quite dare? Or don't I? Like English lasses on a Spanish beach wondering whether or not to go topless...
Topless - topful - topping - over the top - there's a pun here, struggling with its zips and trying to emerge into the open air. So far the bag has mostly been taken up by serious long-distance types, and of course the Special Forces. But even on a simple tropical beach sleep-out, it does make all the difference not to have the morning dew joining you in bed. Or take a bottle of whisky to the first flat place above the youth hostel and join Prince Charlie in the heather.
They are the best of nights: they are the worst of nights. The modern lightweight tent has opened up the wilderness - but for an increasing number of people, the lightweight tent is just a bit too civilised. Can you really experience nature's rawness from inside a zipped-up storm-flap? For those who want to bring a bit of old-fashioned pain and suffering back into the outdoor experience, the bivvybag is the place to be.
In a tent you have to unbag, boot up, and crawl all over a sleeping companion to see what the stars are up to. In a bivvy, the stars are shining right down onto your nose. When the moonlight falls onto a sea of cloud, and the Isle of Skye floats across the sea like a silver dream - do you really want to be zipped up under a green dome asleep? And when the wind howls in the heather and the rain gradually trickles in, you don't experience the full misery when you recline in waterproof tented splendour. If you like to travel a nice short distance with a comfortingly heavy pack, and to spend the sunset hours lying in a cramped green space rehydrating little packets over a cooker, then what you want is a tent. Or perhaps a Youth Hostel, or hotel. But if you want to walk right across the Lakes in a weekend, or right across Scotland in a week - if you prefer a small portable rucksack with no oppressive luxuries (like Karrimats, dry clothing, or cookers) to interfere between you and the mountain experience - then you want the little green bag.
Apart from anything else, a tent won't ever fit onto that ledge of Sgurr na Ciche.
