But due to this weekend’s event taking part virtually, the 25-year-old amputee will be able to complete the 26.2 miles in memory of his aunt and one of his former support worker.
Harley, who has multiple disabilities including autism and Tourette’s syndrome, will be doing the marathon for Rowans Hospice with mum Vanessa on Sunday.
Harley, whose right foot was amputated in 2018, will be using his Alinker walking bike, having used it to complete last year’s Great South Run.
Vanessa said: ‘Since the Great South Run last year, Harley has just gone from strength to strength and has participated in many running and walking challenges.
‘When he undertakes the virtual London Marathon for Rowans Hospice this Sunday, he is and will likely be the only person ever to participate in the official London Marathon on an Alinker, as in its conventional race format his participation could not be accommodated.’
The Alinker bike does not have pedals or a motor but allows Harley to take the weight off his amputated limb.
Harley said: ‘I am taking part in memory of one of my former support workers who was cared for by Rowans.
‘Also, I’m doing it in tribute to my late aunt who died a few weeks ago.
‘She was very special to me and my family and we all miss her very much. While she never got to benefit from the end of life care at Rowans Hospice, she was always keen to support all my fundraising activities.
‘I think she would be so happy to know I’m doing this as a tribute to her.’
Rowans Hospice in Purbrook continues to face cash problems due to Covid-19, with it cancelling its fundraising events and closing charity shops for more than five months.
In June the hospice, which provides palliative and specialist end of life care, launched an emergency fundraising appeal to help it survive.