Every time Brits take a trip to the continent, they're slapped with a great wave of envy. It's not the crustier baguettes or the cheaper wine or membership of the EU for the foreseeable future. It's the double decker trains. Why can't we have them too — WHY?
The short answer is that train networks in the UK are older than those in the rest of Europe, and suffer from low tunnels and different gauges (some of which aren't big enough to carry double deckers). Two world wars meant that heavy duty military equipment had to be transported by rail in Europe — one reason most gauges on the main lines of countries like France and the Netherlands are wieldy enough for double deckers.
The longer answer — and one which rather negates the previous answer — is that Britain DID have double decker trains.
In 1949, the SR Class 4DD was introduced to maybe slightly confused passengers on the route between London Charing Cross and Dartford. About as sexy as a can of Malachite Green Spam with windows can be, the train had a split level floor, with alternately high and low passenger compartments. Overall, the height of the carriages were no more than the usual trains, meaning the double deckers could fit on the network.
The creation of the Chief Mechanical Engineer of the former Southern Railway, Oliver Bulleid, it was hoped the SR Class 4DD could fit almost a third more commuters on board. But things didn't get off to a great start, when the carriages were pulled for moderations after just one day in service. They subsequently had to go through many more tweaks — one of which, in an echo of Boris Johnson's/Thomas Heatherwick's Routemaster snafu, the windows didn't open. In this case, a ventilation system was fitted.
Passenger capacity was actually improved by the SR Class 4DD. The trouble was that none of the compartments were particularly comfortable. Plus, because there were more passengers boarding and alighting, the train service was slowed down.
Only two units of the SR Class 4DD were made, but they put in one heck of a shift — only retiring in 1971 (despite their shortcomings being almost immediately apparent).
Though some cars have since been scrapped, others are apparently still out there. Wouldn't it be something to have one dusted off, and aired at heritage events.
In the meantime, our dream is not dead. Andreas Vogler Studio is currently working on the Aeroliner3000 — a double decker that would run on high speed lines in the UK. It's a darn sight more handsome than the SR Class 4DD, and we dare say it'll be comfier too.