National Rail’s 241 offer permits 1 person free of charge into London Zoo (minimum of 2 visitors required). This offer requires 2 valid national rail tickets and the cheapest, if applicable, of the two visitors goes free. Visitors must pre-book their 241 entry tickets, by entering their promotional code at the beginning of the booking journey. Select the date and time you wish to visit. Your 241 tickets will then appear on the ticket selection page and you can then proceed through the rest of the ticket journey.