The company selling tickets for this year’s Glastonbury festival is preparing for one of its busiest days of the year, when the box office for the event opens on Sunday.

Last year all 177,500 passes to the music and culture concert were sold in a record time of one hour 45 minutes, through a combination of internet and phone-based transactions.

And while demand for this year’s festival is expected to be lower than in 2007, the approaching sale represents a formidable task for the retailer’s resources, said Rob Wilmshurst, chief operating officer at online booking firm See Tickets.

“The demand on the system is enormous, but with effective load balancing in place we can allow as many customers through as can be serviced at any one time,” he said.

“A throttle mechanism above the site allows visitors through in manageable batches. The challenge has always been what to do with all these people, and before we had this technology we used to suffer 100 per cent pro-cessor use, which meant users suffered hung connections or were bounced off the site.”

Since last year, Glastonbury’s organisers have required customers to pre-register their name and address along with a photo, allowing for personalised tickets which combat online touting.

All the data gathered from 2007 was destroyed, but this year’s visitors can opt for their details to be retained to speed up future purchases.

“As soon as the sales are complete, that data will disappear from any web-based server and be held securely elsewhere. It will not even be an electronic file, but locked up in a safe on physical media,” said Wilmshurst.