I smiled gently. 'A man called Wright once wrote about William Ewart Gladstone imputing that he was a hypocrite, particularly in sexual matters. This was in 1927 and Gladstone was long dead. But his son, the then Lord Gladstone, took umbrage and also legal advice. Like Paul Billson, he was told that the dead cannot be libelled, but he nailed Wright to the cross all the same.'

English gave me a wet-eyed look. 'What did he do?'

'He libelled Wright at every opportunity. He called Wright a liar, a fool and a poltroon in public. He had Wright thrown out of his club. In the end Wright had to bring Gladstone to court to protect his reputation. Gladstone had Norman Birkett appear for him, and Birkett flayed Wright in open court. When the case was finished so was Wright; his professional reputation was smashed.' I slid the knife home. 'It could happen to you.'

English shook his head. 'Billson won't do that – he's not the man for it.'

'He might,' I said. 'With help.' I twisted the knife. 'And it will give me great pleasure to appear for him and to swear that you told me that you thought his father to be dead, in spite of what you wrote in your dirty little article.'

I rose and left him. At the door of the pub I stopped and looked back. He was sitting in the corner, looking as though someone had kicked him in the belly, knocking the wind out of him.

I had an early lunch and then belatedly thought to ring Paul Billson's half-sister. I had expected to find her absent from home in the middle of the working day but the telephone was picked up on the third ring and a pleasant voice said, 'Alix Aarvik here.'

I told her who and what I was, then said, 'I take it you haven't heard from your brother, Miss Aarvik.'

'No, I haven't, Mr Stafford.'

'I'd like to talk to you about him. May I come round?'

'Now?' There was uncertainty in her voice.

'Time is of the essence in these matters, Miss Aarvik.' A platitude, but I find they tend to soothe people.

'Very well,' she said. 'I'll be expecting you.'

'Within the half-hour.' I rang off and took a taxi to Kensington.

With a name like hers I had envisaged a big, tow-headed Scandinavian, but she was short and dark and looked in her early thirties. Her flat was comfortable, if sparsely furnished, and I was interested to see that she was apparently moving out. Two suitcases stood in the hall and another on a table was open and half-packed.

She saw me looking around and said, 'You've caught me in the middle of packing.'

I smiled. 'Found another flat?'

She shook her head. 'I'm leaving for Canada. My firm has asked me to go. I'm flying tomorrow afternoon.' She made a gesture which was pathetically helpless. 'I don't know if I'm doing the right thing with Paul still missing, but I have my job to consider.'

'I see,' I said, not seeing a hell of a lot. Her mother had come into a windfall of?100,000 but there was precious little sign of it around, either sticking to Paul Billson or Alix Aarvik. I made a little small talk while I studied her. She was not too well dressed but managed to make the most of what she had, and she didn't overdo the make-up. You could see thousands like her in the streets; a typical specimen of Stenographica londiniensis – the London typist.

When I married Gloria I had not a bean to spare and, during my rise to the giddy heights of success, I had become aware of all the subtle variations in women's knick-knackery from the cheap off-the-peg frock to the one-off Paris creation. Not that Gloria had spent much time in the lower reaches of the clothing spectrum – she developed a talent for spending money faster than I earned it, which was one of the points at issue between us. But I knew enough to know that Alix Aarvik was not dressing like an heiress.

I took the chair she offered, and said, 'Now tell me about Paul'

'What do you want to know?'

'You can start by telling me of his relationship with hi; father.'

She gave me a startled look. 'You've got that far already?'

'It wasn't difficult.'

'He hero-worshipped his father,' she said. 'Not that he ever knew him to remember. Peter Billson died when Paul was two years old. You know about the air crash?'

'There seems to be a little doubt about that,' I said.

Pain showed in her eyes. 'Y ou, too?' She shook her head. 'It was that uncertainty which preyed on Paul's mind. He wanted his father to be dead – rather a dead hero than a living fraud. Do you understand what that means, Mr Stafford?'

'You tell me.'

'I arranged for Paul to have psychiatric treatment. The psychiatrist told me that it was this that was breaking Paul in two. It's a dreadful thing to hero-worship a man – your father – and to wish him dead simultaneously.'

'So he had a neurosis. What form did it take?'

'Generally, he raged against injustice; the smart-aleck kind of injustice such as when someone takes credit for another's achievement. He collected injustices. Wasn't there a book called The Injustice Collector? That's Paul.'

'You say generally – how about specifically?'

'As it related to his father, he thought Peter Billson had been treated unjustly – maligned in death. You know about the court case?' I nodded, and she said, 'He wanted to clear his father's name.'

I said carefully, 'Why do you talk about Paul in the past tense?'

Again she looked startled and turned pale. 'I… I didn't know

…' She intertwined her fingers and whispered, 'I suppose I think he's dead.'

'Why should you think that?' . 'I don't know. But I can't think of any reason why he should disappear, either.'

This neurosis about injustice – did he apply it to himself? Did he think that he was treated unjustly?'

She looked straight at me and said firmly, 'Never! He was always concerned about others. Look, Mr Stafford; I'll come right out and say that Paul wasn't -' she caught herself -'isn't too bright. Now you're in security at Franklin Engineering and I'll tell you that Paul isn't a thief or anything like that. He may not be an entirely balanced man, but he's honest.'

'I have no doubt about it, Miss Aarvik,' I said. 'My enquiries are as much on behalf of Paul as they are for Franklin Engineering. The management of Franklin are very much concerned about what happens to their employees.'

That was pious piffle which I hoped she'd swallow. Neither Stewart nor Isaacson had shown a whit of concern.

She said, 'Paul knew… knows he'll never make his way in the world, but he never showed resentment. I knew he found it hard to make out on only two hundred a month, but he never complained.'

I opened my mouth to contradict her and then closed it firmly. I waited the space of ten heart beats before I said, 'Is that all he got?'

'?2400 a year – it was all he was worth,' she said a little sadly. 'But you must have checked.'

'Yes,' I said bemusedly. 'The exact figure had slipped my memory.'

So Paul had been cheating on his sister. He had told her he earned ?2400 a year when he got over three times as much, although according to Hoyland, and now his sister, that was probably as much as he was worth. You think you have a man taped, his life spread before you like a butterfly pinned iff a showcase, and he surprises you with an inconsistency.

I said, 'Did you ever help him financially?'

She hesitated. 'Not directly.'

Slowly I coaxed the story from her. She had been supporting their mother in her last illness. Mrs Aarvik had been dying of cancer painfully and protractedly. Alix paid for a nurse and private hospital treatment and, towards the end, for the services of a specialist – all beyond the stark necessities of the National Health Service. It was very expensive and her savings ran out.