Can overseas visitors take advantage of 2 for 1?
Although the promotion is set up assuming most participants will be from the UK making day trips from their home, there is nothing to stop overseas visitors taking advantage. The hurdle for most visitors is the requirement for a valid train ticket, along with printing out a voucher if you have not planned your trip before leaving home.
It can be a bit confusing for the first time visitor to the UK. Airport trains from Gatwick and Stansted Airports do qualify if bought from the railways , but the Heathrow trains, the Heathrow Express and TFL Rail Heathrow do not. London Underground tickets also do not qualify you for the scheme.