They're just taking note of what the Lo-cost boys do...
No ones making you pay the £1/£1.50/£2 as you could walk from the station (yeah right!), but if you want this little extra then you can pay for it. Just like charges for RyanAir Check-in, sleasyBoarding, etc
Airports will be charging you to stand in thier queues next.
I can see one area where charging would work - charging a £1 for each item taken off you at security. That would stop the tossers who cause chaos by thinking they can take half a gallon of creams, gells, etc with them.