"Without the others?"
"If you like. Just you and me."
"OK," he said. "When?"
But two years passed and I did nothing about it. The proposed Amsterdam trip became less and less real - an emblem of all those tired promises that busy, guilty mothers make. Meanwhile, Raph not only remained passionate about the diary, but also caught up with Anne in years. He turned 13. Puberty kicked in. Suddenly, his legs seemed too long for his body. I caught him scribbling in notebooks of his own.
"It's just so weird, how alike we are," he confided one day. " Sometimes I think she's speaking just to me. If she was still alive now and lived in Clapham, I just know we'd be friends." Moved by the idea and realising that Raph had to see the secret annexe right now, before he outgrew this feeling, I booked the trip.
"I still can't believe this is it, we're actually going," he says as we wait to board the Friday evening flight to Schiphol and he starts using his Boots two-for-the-price-of-one disposable camera to photograph the security guards at Heathrow.
A plane, a super-fast train from Schiphol, a swervy streetcar and a whole lot of photographs later, we're standing in our truly amazing room at the one-year-old Lloyd Hotel, a majestic 1920s building in Amsterdam's regenerated docklands district.
A team of arts curators and designers have turned this one-time migrants' hotel, wartime prison and young offenders' institution into a delicious vision of light, space and comfort. It's hard to say what makes it quite so wonderful, but I suppose it's simply the hotel you would build for yourself if you only knew how. Each of the 116 rooms is different, quirky and inspiring and they all make you feel like jumping on the beds and playing.
And - why has no one done this before? - you can choose between a neat, cute one-star with a shared bathroom, or anything up to a five-star, the wit and luxury of which takes your breath away.
Guess which we're in? Our room is sound-proofed - for bands to practise in. The bathroom is apple-green fibreglass, the walls clad with pine, and the bed - wait for it - is big enough to sleep eight people. A whole band, in fact. Raph sighs with pleasure and declares it "well cool". We eat fish and chips in the friendly restaurant downstairs which feels just like the kitchen at home, only with more tables. You can pick any combination of anything from the menu - and on the shelf behind the counter there is everything else to buy that you might need, from mustard to face lotion to baby wipes.
We sit at a long pine table with other residents - and beyond are comfy cotton sofas strewn with newspapers, where you can dawdle for coffee after. I put my feet up and flick through Dutch design magazines while Raph decides to explore the tempting open steel staircase that scales the side of the room. He comes back 15 minutes later, breathlessly satisfied. "There are computers up there and a cricket game you can do for free." We end the day marooned in our gigantic bed watching late-night TV and eating chocolate cake and drinking milk. Raph wishes he'd brought his drum kit. "Such a waste because the room is sound-proofed."
Next day we ride the number 10 street car into the centre of Amsterdam. It snakes past dark shuttered warehouses, canal boats with scarlet geraniums tumbling over their decks. We bounce up Rozengracht towards Prinsengracht - and then comes the first disappointment. The queue to get into Anne Frank's house - a blur of fleeces and rucksacks - goes right around the block. Raph looks faintly disgusted. "They're just tourists. Bet none of them have even read the diary." He tells me he'd prefer to see the house in peace, with no one else there, and I say that's impossible. And anyway we're tourists too. But our guide says evenings are usually quieter, and it's open till 9pm, so maybe we'll try again before supper.
We console ourselves with shopping - wandering between the gleaming canals, dodging the bikes that threaten to run us over every time we step off the pavement. The Jordaan - basically the square mile or so to the west of Anne Frank's house - is gorgeous - a place to wander and be surprised. Pavement cafés ("Where are the ones where you can get weed? Can children try it?" Raph wants to know) are crammed in between shops selling the coolest, most reasonably priced clothes as well as - to Raph's extreme delight - comic shops and vinyl record stores. I notice he gets tired every time we go in a clothes shop, but recovers full energy every time a comic shop appears. Thankfully, there are enough of both to keep us both awake.
And then every so often we round a corner and there's a secret courtyard garden - walls painted cobalt or blancmange pink, tall lemon-coloured hollyhocks. Sometimes the shutters of a ground-floor building are thrown wide open on to the street and a shop turns out instead to be someone's living room. We gaze in at a whole family crouched around a table laughing and eating mussels from a large steaming pot. The buildings are old and charming and higgledy-piggledly, the people ludicrously happy and friendly looking. Outside on the cobbles, pink-cheeked toddlers or perky terriers are pulled behind bikes in little wooden sidecars. I feel as if we're walking through the pages of a children's book.
"One thing I've noticed about this place," observes Raph, "is there's nobody poor and nobody fat. Which is quite funny when you think of all the pancakes."
Which reminds him that I promised we'd eat lunch at the Pancake Bakery - a dark "historic" place crammed with Japanese and, OK, perhaps not the exact place I would have chosen were my companion not 13. Worth it, though, to see him in heaven, since I allow him to skip the savoury course and move straight to the bananas, whipped cream and chocolate sauce option.
A quick rest back at our hotel - Raph is back on the computers while I take an apple-green fibre-glass bath, surprisingly comfortable - and then it's out again to have another look at the Anne Frank queue. But at 7pm it's as bad as ever so, longing for a vodka, I suggest we hang out awhile in the shiny white bar next door and hope it gets shorter. Raph rolls his eyes. "You just want a drink." I bribe him with a 7-Up and cheese cubes which he accepts with sulky bad grace. But I was right because 20 minutes later, at ten to eight, we sail into the museum almost without a wait. "Well yeah, apart from the two years," Raph reminds me, just in case I'd forgotten.
It's hard to describe how it feels to trail behind a 13-year-old boy who is walking into
a piece of history, a part of his own emotional landscape and a devastating reminder of man's inhumanity to man, all at the same time. I try hard not to be too much of a parent. I try not to speak and point things out. Though I stand behind him, I try to let him see it all in his own way and his own time. I try not to watch him as he stands in shattered silence in front of the flickering reel which tells Anne's story briefly in a smattering of her own words. Dusk is just darkening the sky as we climb the tight wooden staircase up to where the bookcase still marks the entrance into the secret annexe.
Raph stands in each of the rooms, looks out of the windows, puts his face close up to the yellowed cut-out movie stars still stuck where Anne pasted them on her bedroom walls. A quick glance at the shared toilet. Then he doubles back to look once more down the long stairs that lead to Otto Frank's office and the clamour of the outside world. He spends the longest time in front of the book that lists Anne's death in tiny print alongside so many others. His face is blank with pure concentration. Then, without a glance, he turns and continues down the stairs.
In the bookshop, he rejects anything about the museum and asks just for a simple poster with Anne's familiar thin, eager face on it. He clutches it to his chest as we exit on to Prinsengracht where the evening seems suddenly loud and bright.
"It's not that I'm jealous or anything," he says quietly after a few minutes of walking. "But it is very hard to believe that all those people in there feel what I feel. I mean, it's obvious they don't really care."
I point out gently that he can't make that judgement. He can't know to what extent other people do or don't care. "Yeah but..." he says and after that we walk for a long time in silence and I'm torn between wanting to help him to understand that he doesn't own Anne - and wanting to help him maintain the sad intensity and romance of his relationship with her.
In the Indian restaurant on Harlemmerdijk however, he brightens when he sees a man outside being led away by police in handcuffs. "I bet it was crack cocaine," he says. "He wouldn't have been arrested if it was only weed because weed's legal." He takes a breath. "Mum, I've decided I'm definitely going to live here when I'm older. How long do you think it would take to learn Dutch? Could I do it on the internet?"
The writer travelled as a guest of KLM and Special Hotels of the World. KLM (08705-074 074; www.klm.com) offers return flights from London to Amsterdam from £69.
Double rooms at the Lloyd Hotel cost from €64 (£46) to €300 (£214) per night without breakfast. For reservations contact Special Hotels of the World (0800-032 8212; www.shotw.com ) or see www.lloydhotel.com
Our favourite transport
Raph: I liked the way the trams were so clean and silent, and kinked in the middle so they could swerve around the corners, though several times my mum made us get on the totally wrong one going in the opposite direction from where we wanted to go.
Mum: The streetcars were really easy to work out and stress-free. Actually, we hardly ever went wrong.
Our favourite luxury
Raph: I've never been allowed room service and I've never slept in a bed for eight people either - so eating cake late at night stretched out in luxury with the television on was perfect.
Mum: Drinking cold Chablis in a giant bed isn't bad either. But given how reasonable the Lloyd Hotel is in every way, the €10 charge for room service seemed unnecessarily steep.
Our favourite shops
Raph: The shops were really cool. There was one which had every type of drumstick you could imagine and another full of Marvel comics and figures, and one with Mexican stuff - I bought a ring. One shop sold just toothbrushes and had a whole display of them going round in the window.
Mum: There are lots of great independent boutiques for interesting clothes at very affordable prices. Stick to the Jordaan and don't even go near Kalverstraat with its depressing chain stores, unless you want to feel like you're on Oxford Street.
Our favourite food
Raph: I did love the pancakes at the Pancake Bakery on Prinsengracht, but I think my best meal was the Indian meal we had. I thought it was better than London, but that might just have been the atmosphere and being out late in a strange place.
Mum: The food at Lloyd Hotel was especially good for kids/teenagers because you are allowed to pick and mix exactly as you want from a menu which is just like home.