The Invisible Code (25 page)

‘Sorry, there was one other thing,’ said Porter. ‘We closed the walls because I thought it wasn’t a good idea to have visitors looking in.’

‘What do you mean?’

The curator pointed to the polished brass handles that were set in the walls. She reached over and pulled the first one.

The wall was hinged in the middle and folded back, revealing a second wall of paintings. She proceeded to walk around the little gallery opening each of the walls in turn until she had revealed a completely different set of pictures. May was amazed to see another set of handles on these inner walls. Porter pulled at these and the second set of walls folded back on three sides. The fourth pair revealed that the room was, in fact, open to the atrium on one side. From here you could see into the rest of the
house, up to the skylight and down to an empty Egyptian sarcophagus in the basement.

‘Sir John Soane had trouble storing all of his treasures,’ she explained, ‘so he arranged for the paintings to be hidden behind each other.’

‘Wait – which one of these sets of walls was open when you found the body?’

‘The middle ones.’ She closed the set of doors above the spot where the body had lain.

May found himself looking at William Hogarth’s paintings of
The Rake’s Progress
. ‘Tell me she wasn’t leaving us a clue,’ he groaned. ‘Nobody does that for real.’

‘It’s either the paintings, the ceiling or heaven,’ said Banbury, opening his kit and setting to work. ‘Ask Mr Bryant. If it’s something to do with one of the pictures, he’s bound to know.’

26

THE CARDANO GRILLE

ARTHUR BRYANT’S TAXI
brought him from the station to Bletchley Park at 11.45 a.m. The mansion had been built by a wealthy city financier in 1883 and finished in a bizarre mix of architectural styles, crenellated and gabled, with Tudor beams, decorative cream stonework, turrets, arches and redbrick octagonal rooms, one with a green copper dome.

In the Second World War it had been rechristened Station X and filled with MI6 codebreakers who masqueraded as ‘Captain Ridley’s Shooting Party’ to disguise their true identities. Here Alan Turing and his colleagues had cracked the secret of the German Enigma machine, following a path of discovery that would eventually lead to the birth of the modern computer.

Angela Lacie was a former MI6 cryptography expert who had retired to help raise sponsorship for the restoration of Bletchley Park. As she swung down the stairs Bryant saw her as he had first seen her not long after the war: an elegant no-nonsense scientist in a boxy suit, with her blonde hair in slides made from wire clips tied with
beads; there had been no money for fashion items, and the MI6 girls had made their own.

Her hair was ash-coloured now but she had kept her figure and her smile. ‘I wonder what it’s taken to get you to visit me,’ she asked, giving him a hug. ‘You smell of disinfectant.’

‘Wintergreen mixture.’ Bryant bared his false teeth to reveal a bright green boiled sweet. ‘I need your help.’

‘I rather thought you might. You know I’m still under GCHQ employee rulings, so there won’t be much I can tell you.’

‘This won’t compromise you, I promise,’ Bryant assured her.

‘Let’s go to the day room. There’s less chance of appearing in the background of tourist photographs in there.’

They walked through the ground-floor visitors’ centre to the rear, where Angela pushed open a door leading to a small sunlit conservatory fitted with empty refreshment tables. She poured tea from an immense urn.

‘I can’t be long,’ she warned. ‘I’ve got a big Polish delegation in shortly. Polish cryptographers were fundamental to the breaking of the Enigma Code, and we’re seeking to honour their contribution.’

‘You mean you’re trying to get money out of them,’ said Bryant. ‘I wonder what poor old Alan Turing would say if he could see how ubiquitous computers have become.’

‘I imagine he’d be thrilled.’

‘Funny how it’s always society’s outsiders who create the things that bind society together. Other countries venerate their national heroes. What did we do to one of our best minds? We chemically castrated him. Any biscuits going?’

‘Here.’ She passed him some Garibaldis. ‘I suppose
you’re still smoking that disgusting pipe. And I’m sure you were wearing that scarf the last time I saw you.’

‘Remind me when that was?’

‘The winter of 1985. Something to do with a woman found strangled in a Carnaby Street shop window. How are you?’

‘Well, it never gets any easier. Sometimes I doubt myself. I’m probably having a mid-life crisis.’

‘You’ve left it a bit late.’

‘I didn’t say which life.’

Angela laughed. ‘Come on, then, what have you got for me?’

Bryant poked about in his overcoat and pulled out the thank-you card and envelope. ‘This was sent to me in yesterday’s mail. Take a look at the inside.’ He passed it over.

Angela carefully opened the envelope, and holding up the card between her thumb and forefinger, raised it to the light. The back half was striated with two sets of narrow slits, the top four vertical, the bottom four horizontal. ‘Oh Arthur, you didn’t need to come to me with this, you could have gone to a toyshop and figured it out.’

‘I’m assuming you haven’t been near a toyshop in a very long time, Angela. Children only like flying robots that fire lasers now.’

‘When I was a little girl I spent my days with bits of paper, making up codes.’

‘And I built Spitfires, but children aren’t allowed knives and glue any more. This also requires the use of a sharp knife – or a pair of nail scissors, which I believe the sender has.’

‘Then I guess you already know what it is.’

‘I wanted confirmation.’

Angela turned the card over and examined it carefully. ‘Well, it certainly looks like a Cardano grille. A four-hundred-year-old cryptographic technique. They were
still in use during the last war. I often made them with my schoolmates. I read somewhere that kids still play with them in parts of Eastern Europe. Not having money for toys makes you inventive.’

‘So how does it work?’

‘Easy. You cut some slots the height of a line of text in a piece of card, write in a ciphertext, remove the card and fill the rest in with anything you like. To decode the message the receiver places a similar card over the text. Where’s the other part? Your friend, what did she put these over?’

‘I don’t know. There wasn’t anything else. What’s the difference between a code and a cipher?’

‘A cipher’s an algorithm, a series of steps for encrypting a message, and a code usually uses a key. There are hundreds of ways of doing it, but the simplest is to use a key like the Caesar shift.’

Angela took out a pen and began lettering her napkin. ‘You write out the alphabet, then underneath it you do the same again, but change the order of the letters. Julius Caesar kept his messages secret by shifting the second line three places to the left. An additional trick is to start with a short keyword, then follow it with your text. If that eludes you, there are still various ways to decipher the message. You could “garden” for it, which means you contact the other party and ask them questions which encourage the use of certain words in their reply, or you can look for common repeats – words like “can”, “you” and “today”. Or you can overlay a second encryption. It was a great Victorian pastime, coming up with ways to hide messages. The personal columns of
The Times
were filled with cryptic messages sent between couples, sometimes over decades. One of Edward Elgar’s best-known compositions became known as the Enigma Variations because he wrote part of his programme notes in a code that has never been broken.’ She handed the
card back to Bryant. ‘You need the message page that goes with it.’

‘I don’t know what she did with that.’

‘Then why bother to send this if she didn’t tell you where you could find the other part?’

‘She wasn’t thinking clearly. She’s been unwell for a while.’

‘I’m sorry I couldn’t be more helpful.’

‘This message – what would it look like?’

‘Well, the lettering would be of a point-size that could fit into those card slots. An old trick is to retype it and bury it in a bunch of other throwaway stuff – notes, receipts and so on.’

‘In that case I think I might know where to find it. Angela, you should take off the “a” – you’re an angel.’

‘Well, you’ll never know, will you? You had your chance once, long ago, but you didn’t take it.’

‘Didn’t I?’

‘No, you arranged to meet me and never showed up.’

‘No, I distinctly remember showing up – you didn’t.’

‘I most certainly did, Arthur. I waited for you on Waterloo Bridge in the rain for a whole hour.’

‘You should have been able to see me, then. I was on Blackfriars Bridge. I waited for ages. You must have failed to understand my message. Not very impressive for a codebreaker.’

‘Oh,
Arthur
.’

‘We could always pick up where we left off.’

‘I think my husband and my five children might object to that.’

‘Ah. No doubt.’ Bryant rose and planted his hat on his head. ‘Well, you were very helpful.’

‘Give my regards to your lovely partner. And, Arthur …’

‘Yes?’ Bryant’s watery blue eyes swam up at her so sweetly that she wanted to give him a cuddle.

‘Please’ – she picked a piece of lint from the frayed collar of his coat – ‘do try to look after yourself.’

Bryant smiled vaguely and set off back to London, still thinking about being on the wrong bridge.

27

THE WARNING

BRYANT WAS AMAZED
to see the unit’s common room in a hurricane of activity. ‘Why the hell is your phone turned off?’ May asked. ‘We’ve been trying to get hold of you for ages.’

‘It’s not turned off,’ said Bryant. ‘I even recharged it before I left. Oh.’ The object he removed from his pocket bore very little resemblance to a mobile. It was covered in what appeared to be sticky black tar.

‘What on earth is that?’

‘Liquorice Allsorts. I had a bag of them in my pocket. I left my coat lying on a tea urn at Bletchley.’

‘Sabira is dead. I’ve just come off the phone from talking to Kasavian. He’s – well, you can imagine. They’re taking the body to Giles at St Pancras.’

‘Lumme, that’s horrible,’ said Bryant, not sounding unduly surprised.

‘Obviously, there are going to be horrendous repercussions. Take a look at these.’ May passed Banbury’s laptop to his partner and thumbed through the photographs of the crime scene.

‘What killed her?’ Bryant asked.

‘We’ve no idea yet. There are no obvious marks on the body, but the EMT think she had trouble breathing. We’ve already managed to track her movements through her Oyster card and her phone. She slipped out of the clinic first thing, caught a Tube to Baker Street and went to the Regent’s Park mosque, then headed down into Holborn and was found dead on the first floor of the Sir John Soane Museum.’

‘The Soane? Why would she go there?’

‘We’ve no idea yet. The duty nurse at the Cedar Tree said she’d been behaving more strangely than ever, talking to herself, exhibiting signs of paranoia.’

‘That can’t kill you, John. Something else must have happened. Who else was in the museum?’