Heathrow express see through clothes scanner trial

I heard this on the radio this morning.

"The Independent reports some details about the 4 week trial of the "see through your clothes" passive millimetre wave imaging scanner which has been installed at London's Paddington mainline railway station on the Heathrow Express platform."

Spy Blog has some legitimate concerns:

"80 seconds per scan, minimum !!

Since the Heathrow Express service leaves Paddington every 15 minutes, that means that passengers (who will certainly be struggling with suitcases on their way to the airport) will miss the next train on which they have booked their tickets / reserved their seats, if there are as few as 10 or so people in the queue ahead them to be scanned...

if the "randomly selected" passengers are Children. The operators will be guilty of "creating or distributing" Child Pornography, a term which includes synthetic digital images. If children are automatically excluded, then the whole system is useless against smugglers or terrorists...

what aspect of the "technology" is being tested on the public ?

What does this prove that a group of paid experimental test subjects could not ?

The ability to see people naked throough various types of clothing ? The ability to detect various deliberately concealed items ?

How can this be a scientific test, if the data is really destroyed after each scan ?

Where is the proof that this system is safe for, say, pregnant women ?

Will people who refuse to be scanned be treated as "terrirst suspects" and stopped and searched under the Terrorism Act 2000 section 44 anyway ?"