On Saturday 12 September 2026, I will run the Thames Path Challenge from Putney Bridge to Henley-on-Thames. A distance of 100km (60 miles).

Why? To raise funds for Leni, the 2 year old grand-daughter of long standing family friends, the Forresters. Leni has devastatingly been diagnosed with an extremely rare and very severe rapidly neurodegenerative genetic condition called Sanfilippo Syndrome Type B (MPSIIIB), also known as Childhood Dementia.

Children with this condition have a defect in a single gene that prevents them from breaking down a sugar molecule called heparan sulfate, causing toxic waste to build up in the brain and body.

Sanfilippo Syndrome is unimaginably cruel. Children develop relatively ‘normally’ with no obvious symptoms until they are around two years old, then over a short period of time they lose all the skills they once learned, experience severe behavioural challenges, hyperactivity, insomnia that can last for days, seizures, a total loss of cognitive and motor function, and a premature death in their early to mid teens, as well as many other horrific symptoms. Sanfilippo is relentless and leaves nothing untouched.

You can read more about Leni and the impact of Sanfilippo on her main fundraising page .

There is no cure and currently no approved treatment. However, there are promising experimental enzyme replacement treatments and gene therapies that Leni may be eligible for this year. Some of this research is taking place at the University of Edinburgh, my alma mater.

Leni's incredible parents, Emily and Gus Forrester, are working tirelessly to raise awareness of the future that faces Leni and children like her, and try to secure access to treatment. Funding is part of what is standing in their way. They have already raised huge sums but still need more, not just for Leni but hopefully for other children affected by this awful condition.

These treatments have shown extraordinary early results but with Leni’s condition, weeks and months really matter so the issue is urgent as the damage caused by the condition cannot be undone.

I would be honoured and extremely grateful if you would be able to help me support them by raising additional funds for Leni and awareness for other children suffering with the condition. Please share this page with your friends and families to spread the word.

If you can, please donate: every contribution makes a real difference. All funds raised through this page will go directly to Emily and Gus’s main fundraising efforts.

Emily and Gus have also been raising awareness of Leni and her condition. You can read/watch some of the coverage in these links:

Independent

Daily Mirror

ITV news

More details of the Thames Path Challenge event can be found here .