With a practised hand the senior partner motioned a waiter to bring a fresh pot of coffee and five more pipes of tobacco.

'But if we withdraw all our clients' money from the South Sea Company,' the broker was saying, 'isn't that going to cause a crisis of confidence?'

'Maybe,' said the senior partner. 'So what?'

'But ...' The broker, lost for words, waved his hands about. His colleague took up the argument.

'If the public get the idea that there's something wrong with the South Sea Company,' he said, 'the effects could be catastrophic. There would be an immediate collapse. The economy of the nation - of Europe even - would

The senior partner cut him short with a wave of his hand. 'Listen,' he said, 'Mr, er...'

'Smith,' said the broker's friend, 'Adam Smith.'

'Mr Smith,' the senior partner went on, 'you haven't answered my question. So what? All your funds will be safely invested in Second Crusade 67% Unsecured Loan Stock. What possible difference will it make to you if the whole British economy crumbles away into dust?'

Mr Smith's lower lip quivered slightly. 'But that's -' he started to say.

'In fact,' the senior partner went on, 'what could be better, from your point of view? Sell now, reinvest, buy back at the bottom of the market, make a double killing. The wonderful part of it is that, thanks to the unique facilities offered by our Simultaneous Equities Managed Fund, your money can be invested in both the Second Crusade and the slow but steady regrowth of the British economy at the same time. Well, concurrently, anyway. There is a technical difference, but I don't want to blind you with science.

'I ...' Mr Smith stuttered, but his friend the broker stopped him.

'Actually,' he was saying, 'I rather like the sound of that.'

The senior partner smiled. 'That's the spirit,' he said. 'Now, if we can move on to the topic of life a.s.surance, we offer a wide range of tailor-made retrospective endowment policies which -'

'Hold on,' Mr Smith interrupted, 'hold on just a moment.

The partners turned and looked at him. 'Well?' they said.

'Gentlemen.' Mr Smith calmed himself down into an effort. 'You may not be aware of this,' he said, 'but I am by profession a student of economic theory; in fact, I pride myself on being on the verge of a breakthrough in monetary a.n.a.lysis which will, I sincerely believe, revolutionise the practice of economic planning in Europe, and my view is -'

'You mean,' said the senior partner slowly, 'The Wealth of Nations?'

Smith's jaw dropped. 'You've heard of my book?'

'Naturally.'

'But that's impossible,' Smith replied. 'Why, I only completed the final draft today. In fact, I have it with me now. I'm taking it to my publisher.'

The senior partner smiled politely. 'You have the actual ma.n.u.script with you?' he said.

Smith, in spite of himself, could feel a glow of pride creeping over his face. It had been a long time since anyone had taken him seriously, since he'd been shown the proper respect his genius merited. 'I do indeed,' he said.

'Really!' The senior partner's manner changed; he became deferential. 'I have indeed heard of your work, Mr Smith,' he said. 'The word "seminal" would not be an overstatement.' Smith blushed. 'In fact, I would go further and say that your book brings the Dark Ages of economics to an end. May I see?'

After a very brief moment's hesitation, Smith dived into his battered brown bag and produced a ma.n.u.script. It was thick, dog-eared and bound up in red string. He handed it to the senior partner, who threw it on the fire.

'Now then,' he said, 'we offer a wide range of tailor-made retrospective endowment policies which ...'

'You really must learn,' Blondel said, 'to be more careful with that thing.'

'I wasn't

'I mean,' Blondel said, 'it's a nice trick if you can do it, but there are some people who have very pointy tops to their heads. You could injure somebody that way, you know.'

'It wasn't -'

'Anyway,' Blondel leaned against the wall and caught his breath. 'I don't think they're following us, do you?' he panted.

'No.'

'Splendid. Now, where are we, do you think?' He produced his little book and began to study it. Guy, who had got out of the habit of running shortly after leaving school, leaned with his hands on his knees and gasped for air.

'Blondel,' he said, 'I nearly killed Oliver Cromwell.'

'I know,' Blondel replied. 'Now, I make that the Un-American Activities archive over there, so if we head due south...'

'I nearly changed the history of the world.'

'Then we can take a short cut through the New Deal, which ought to bring us out where we want to be. Sorry, you were saying?'

'History,' Guy repeated. 'I could have really messed it up, you know?'

'Exactly,' Blondel replied. 'Very volatile stuff, history. Give you an example. You tread on a fly. The fly is therefore not available to walk all over your great-great-great-great-grandfather's breakfast, and so he fails to die of food poisoning. Your family therefore does not sell up and move from Cheshire to Norfolk, with the result that your great-grandfather doesn't meet your great-grandmother at a whist drive, and you don't get born. That means you never existed, so you can't travel back through time and squash that fly in the first place. Result: your great-great-great-great-grandfather gets food poisoning, the family moves from Norfolk to Cheshire ...'

'And you,' Blondel went on, 'become a temporal anomaly, zipping in and out of existence like the picture on a television screen, thousands of times a second. Then you start to cause real problems, because of the knock-on effect and Ziegler's Mouse, and you end up with the Time Wardens after you.'

'Time Wardens.'

'Like game wardens,' Blondel explained, 'only with even more sweepingly wide powers. They won't be appointed for a hundred years or so yet, but when they are they'll travel back and start rounding up all the Loose Cannons.'

'Loose Canons,' Guy repeated. 'Is that some kind of religious order?'

'Not quite,' Blondel replied. 'You're thinking of the Giggling Friars, which is odd enough in its way, because they were all wiped out by the Time Wardens in about six hundred years' time. The Wardens have been looking for me since before I was born,' he added, 'or at least they will be. Actually they're not a problem. It's the bounty hunters you've got to be wary of. Now, I think that if we go along this pa.s.sage here, we'll come to a sharp left bend which should ... ah, here we are.'

As far as Guy was concerned it was just another tunnel, but Blondel seemed to recognise it at once. He said, 'Nearly there,' several times, and whistled a number of tunes, including Stardust and The Girl I Left Behind Me.

'History,' he was saying, 'is fluid: you've got to remember that. It's changing all the time, what with the Loose Cannons and the Time Wardens and the Editeurs Saunce Pitie. Now then, if I press this lever here...'

A door opened, and Blondel walked through it.

Experience, the psychologists say, is like a man who walks into a lamppost, knocking himself out. When he comes round, the blow has caused a partial memory loss, which means that the victim forgets, inter alia, that colliding with lampposts causes injury. He therefore continues walking into lampposts for the rest of his unnaturally short life.

'Blondel,' said Guy, but Blondel wasn't there any more. He shrugged and followed.

'L'amours dont sui epris