Mr Smith goes to . . . the mail rail

The seasonal post goes underground

If there's a more Christmassy conveyance than the Post Office's Mail Rail, then it can only be Santa's sleigh itself, unless it's a police van in a town centre after last orders. But the Royal Mail has indicated that this may be the last festive season on which it operates its miniature railway underneath the streets of central London. So we had better make the most of this train set while we can.

If you ask nicely, you can have a go on it at Mount Pleasant sorting office, or at least you can watch it whirring around in the basement. As the lift doors sigh you out on to the platform 70 feet below ground, however, you realise that you are not in a hobbyist's cellar but the lair of an evil genius, or rather, a guileless apology for one. It's as if the Wizard of Oz and Austin Powers's nemesis, Dr Evil, had taken up a PPP franchise for the Tube. A red LED display shows the icon of a puffing loco and indicates that the next train is temporarily at rest at a location identified only as "E14".

When the first driverless service made the subterranean journey between Paddington and Whitechapel 75 years ago, the idea was to stop deliveries being delayed by those pesky horse-drawn carriages and omnibuses. Ever since, letters, parcels and Christmas post have been dropped down chutes from sorting depots into the wagons below. But managers say the Mail Rail now costs five times more than vans.

The train pulls into Mount Pleasant station and it's clear at once that it doesn't merit the lusty LED of the signage. On such transportation might Ken Dodd's Diddymen have embarked for the face of the chip-butty mines of Knotty Ash. I suppose it could conceivably have taken Oddjob to Blofeld's compound, but only if he'd ducked whenever the train went into a tunnel. It seemed made to measure for Mini-Me.

The other association I mentioned was with the Wizard of Oz. The secretive railway was like the fantastic palace of Oz, with one major caveat. The twist about the Wiz was that a pint-sized illusionist was behind all the bigger-than-life special effects. But the same pay-off was never likely to await the visitor to an already dwarfish project like the Mail Rail. On the contrary, the thrills and spills all had to work the other way around, if you follow me.

Sure enough, when I put my head around the door of the signal box, I couldn't fail to notice the giantism suffered by the unfortunate controller. His affliction had led him to seek a job far from his fellows. Years of torment made him look at me in silent entreaty from his great height of not less than 5'10". Shamefaced, the Monster of Mount Pleasant pressed a doodad suspended from the ceiling in order to dispatch another train. He looked as if he was firing up the conveyor belt in a sushi restaurant.