It's not much of a surprise that Transport Secretary Alistair Darling has announced that x-ray screening can't be implemented across the rail network. Well of course not, there are so many entry points to the rail network that the cost of the machines and staff would be absurd, never mind that they could never cope with rush-hour numbers.
Instead of just focussing on other measures, such as better trained police and human intelligence agents (though they're doing a bit of that), they're going to be piloting x-ray and body scanner machines on the Heathrow Express line. A complete waste of time and money, the usual cheap politics of the ignorant I'm afraid.
This is a classic case of fighting the last war we lost. I'd expect the next attack to be a car or truck-based bomb and not to be train or tube-based considering the excessive police presence on the networks now.
By so publicly announcing the location of where these machines will be it's certain that no serious terrorist is going to actually use that rail line or any others that have scanners installed in the future.
If airports are anything to go by then the people staffing these machines will be underpaid and bored right out of their brains. Due to passenger numbers they'll have to pick only some people, which due to their low training and motivation will probably the 'usual suspects' if the scanning staff do any profiling at all.
Of course this makes it look like 'something is being done' by the politicians (and I'm not saying something shouldn't be done) but it's just using technology to cover the hand waving. The public know about airport screening so it sort of sounds good, sounds reassuring etc. But in reality this, if anything, makes us more insecure by diverting resources and attention away from more useful security measures like: Making it harder to produce high explosives, effectively tracking terrorist networks, interfering with their funding (if you think we're doing well on that count read this damning report ) and so on.
The UK isn't the only place doing this kind of silly security measure for public reassurance, the US are masters at it too… the problem is a lack of proper security understanding in many segments of the non-security service government and a lack of criticism on these matters from the media because, well we've all got to be seen to want the terrorists stopped. We do, which is why it's important we point out the stupid ideas when they arise.
Fun bonus link, by the ever excellent John Lettice, showing why two biometrics are not always better than one