I would rather o2 spend it's resources ensuring it meets its coverage obligation (already done at the arena) around the country before boosting root metrics scores. Once the 95% has 4g then improve customer experience .
Speed of data at a music venue can only aid in the piracy and copy rite infringement of the artists.
As long as you can make a phone call to book a taxi etc, data at these places should be a luxury.
Just my take