Don’t panic. London has a 24-hour addiction to shopping. If the Oxford Street Sports Direct is closed, you can always hit the one at Westfield or the other one on Brent Cross. They keep different hours, so you’re never truly stranded.
Or, you know, you could just go home, order the same trainers online, and wait forty-eight hours while eating crisps in your pajamas. That’s a valid option, and I fully support it.