From an email from Southbank: "It is against Southbank Centre's terms and
conditions to resell tickets, including using third party websites such
as Viagogo, Getmein and Stubhub. Any tickets that are resold will be
cancelled and the purchaser will be refused admittance.
If you can no longer make the event you can exchange your tickets for a
credit voucher up to 48 hours before the concert. To prevent resale, we
are going to post tickets and email e-tickets so that you receive them
7-10 days prior to each event"
Thanks,
@mattsmudge.