If anyone is interested...the Tooting 24hr event is an annual thing. It's been going for years and was founded by an Indian chap who believed in running as a way of meditating.
https://uk.srichinmoyraces.org/london-24#third-section-tab-1
I've tried and failed to do the South Downs Way. I walked from Beachy Head to Falmer before blisters the size of slugs did me in. That's about 25 miles. I've done Brighton to West Worthing a few times after missing the train home.
My brother on the other hand....he's an ultra-marathon runner...