A Coulsdon woman will walk 55km after her friend was diagnosed with a brain tumour.

Bryony Marsden, 34, will take on the South Coast Challenge this Saturday after being "shocked" by the lack of funding for research into the disease.

“My friend’s diagnosis came completely out of the blue," she said.

"I want to help people who find themselves in a similar position by completing my triathlon and, in doing so, I hope to inspire others to pick up a bike, running shoes or swimsuit in pursuit of a cure.”

This mammoth walk is the second challenge she is taking part of in her ultra-marathon to raise money for the Brain Tumour Research charity.

In July, she tackled a 12-hour indoor cycle and in September she will complete a mile-long open water swim in Hackney.

“Having previously run the Ugandan Marathon and also having completed a six-day trek in Peru, I am looking forward to my next sporting test," Bryony said.

"Though I’ve been training hard, I am sure the South Coast Challenge will be tough and I will have a few blisters as I cross the finish line.

"I’m also hoping the weather isn’t too hot on the day.”

You can go to Bryony’s JustGiving page here to donate.