英国的2 for 1究竟是什么优惠？怎样使用？哪里有

get the voucher list from a train station which has train to London first.
Then when you and another person go there, fill the details on the voucher, show them the voucher and your tickets TO LONDON, and then will allow both of you into the place and charge for 1 person only- that is the basic logic.

http://www.daysoutguide.co.uk/2for1-london 2 for 1的网址，希望对你有帮助。