So the place is mine.

I suppose my father is about forty-five now, though sometimes I think he looks a lot older, and occasionally I think he might be a little younger. He won't tell me his real age, so forty-five is my estimate, judging by his looks.

"What height is this table?" he said suddenly, just as I was about to go to the breadbin for a slice to wipe my plate with. I turned round and looked at him, wondering why he was bothering with such an easy question.

"Thirty inches," I told him, and took a crust from the bin.

"Wrong," he said with an eager grin. "Two foot six."

I shook my head at him, scowling, and wiped the brown rim of soup from the inside of my plate. There was a time when I was genuinely afraid of these idiotic questions, but now, apart from the fact that I must know the height, length, breadth, area and volume of just about every part of the house and everything in it, I can see my father's obsession for what it is. It gets embarrassing at times when there are guests in the house, even if they are family and ought to know what to expect. They'll be sitting there, probably in the lounge, wondering whether Father's going to feed them anything or just give an impromptu lecture on cancer of the colon or tapeworms, when he'll sidle up to somebody, look round to make sure everybody's watching, then in a conspiratorial stage-whisper say: "See that door over there? It's eighty-five inches, corner to corner. " Then he'll wink and walk off, or slide over on his seat, looking nonchalant.

Ever since I can remember there have been little stickers of white paper all over the house with neat black-biro writing on them. Attached to the legs of chairs, the edges of rugs, the bottoms of jugs, the aerials of radios, the doors of drawers, the headboards of beds, the screens of televisions, the handles of pots and pans, they give the appropriate measurement for the part of the object they're stuck to. There are even ones in pencil stuck to the leaves of plants. When I was a child I once went round the house tearing all the stickers off; I was belted and sent to my room for two days. Later my father decided it would be useful and character-forming for me to know all the measurements as well as he did, so I had to sit for hours with the Measurement Book (a huge loose-leaf thing with all the information on the little stickers carefully recorded according to room and category of object), or go round the house with a jotter, making my own notes. This was all in addition to the usual lessons my father gave me on mathematics and history and so on. It didn't leave much time for going out to play, and I resented it a great deal. I was having a War at the time — the Mussels against the Dead Flies I think it was — and while I was in the library poring over the book and trying to keep my eyes open, soaking up all those damn silly Imperial measurements, the wind would be blowing my fly armies over half the island and the sea would first sink the mussel shells in their high pools and then cover them with sand. Luckily my father grew tired of this grand scheme and contented himself with firing the odd surprise question at me concerning the capacity of the umbrella-stand in pints or the total area in fractions of an acre of all the curtains in the house actually hung up at the time.

"I'm not answering these questions any more," I said to him as I took my plate to the sink. "We should have gone metric years ago."

My father snorted into his glass as he drained it. "Hectares and that sort of rubbish. Certainly not. It's all based on the measurement of the globe, you know. I don't have to tell you what nonsense that is."

I sighed as I took an apple from the bowl on the window sill. My father once had me believing that the earth was a Mobius strip, not a sphere. He still maintains that he believes this, and makes a great show of sending off a manuscript to publishers down in London, trying to get them to publish a book expounding this view, but I know he's just mischief-making again, and gets most of his pleasure from his acts of stunned disbelief and then righteous indignation when the manuscript is eventually returned. This occurs about every three months, and I doubt that life would be half as much fun for him without this sort of ritual. Anyway, that is one of his reasons for not switching over to a metric standard for his stupid measurements, though in fact he's just lazy.

"What were you up to today?" He stared across the table at me, rolling the empty tumbler around on the wooden table-top.

I shrugged. "Out. Walking and things."

"Building dams again?" he sneered.

"No," I said, shaking my head confidently and biting the apple. "Not today."

"I hope you weren't out killing any of God's creatures." I shrugged at him again. Of course I was out killing things. How the hell am I supposed to get heads and bodies for the Poles and the Bunker if I don't kill things? There just aren't enough natural deaths. You can't explain that sort of thing to people, though.

"Sometimes I think you're the one who should be in hospital, not Eric." He was looking at me from under his dark brows, his voice low. Once, that sort of talk would have scared me, but not now. I'm nearly seventeen, and not a child. Here in Scotland I'm old enough to get married without my parent's permission, and have been for a year. There wouldn't be much point to me getting married perhaps — I'll admit that — but the principle is there.

Besides, I'm not Eric; I'm me and I'm here and that's all there is to it. I don't bother people and they had best not bother me if they know what's good for them. I don't go giving people presents of burning dogs, or frighten the local toddlers with handfuls of maggots and mouthfuls of worms. The people in the town may say "Oh, he's not all there, you know," but that's just their little joke (and sometimes, just to rub it in, they don't point to their heads as they say it); I don't mind. I've learned to live with my disability, and learned to live without other people, so it's no skin off my nose.

My father seemed to be trying to hurt me, though; he wouldn't say something like that normally. The news about Eric must have shaken him. I think he knew, just as I did, that Eric would get back, and he was worried about what would happen. I didn't blame him, and I didn't doubt that he was also worried about me. I represent a crime, and if Eric was to come back stirring things up The Truth About Frank might come out.

I was never registered. I have no birth certificate, no National Insurance number, nothing to say I'm alive or have ever existed. I know this is a crime, and so does my father, and I think that sometimes he regrets the decision he made seventeen years ago, in his hippy-anarchist days, or whatever they were.

Not that I've suffered, really. I enjoyed it, and you could hardly say that I wasn't educated. I probably know more about the conventional school subjects than most people of my age. I could complain about the truth of some of the bits of information my father passed on to me, mind you. Ever since I was able to go into Porteneil alone and check things up in the library my father has had to be pretty straight with me, but when I was younger he used to fool me time after time, answering my honest if naive questions with utter rubbish.

For years I believed Pathos was one of the Three Musketeers, Fellatio was a character in Hamlet, Vitreous a town in China, and that the Irish peasants had to tread the peat to make Guinness.

Well, these days I can reach the highest shelves of the house library, and walk into Porteneil to visit the one there, so I can check up on anything my father says, and he has to tell me the truth. It annoys him a lot, I think, but that's the way things go. Call it progress.

But I am educated. While he wasn't able to resist indulging his rather immature sense of humour by selling me a few dummies, my father couldn't abide a son of his not being a credit to him in some way; my body was a forlorn hope for any improvement, so only my mind was left. Hence all my lessons. My father is an educated man, and he passed a lot of what he already knew on to me, as well as doing a fair bit of study himself into areas he didn't know all that much about just so that he could teach me. My father is a doctor of chemistry, or perhaps biochemistry — I'm not sure. He seems to have known enough about ordinary medicine — and perhaps still have had the contacts within the profession — to make sure that I got my inoculations and injections at the correct times in my life, despite my official non-existence as far as the National Health Service is concerned.