London 100 is Saturday 10 May 2025. The event will run from 7am to midnight.

London 100 includes the following distances: London 100km ultramarathon London 50km ultramarathon London 25k

London 100 has launched. Registration is here. If you're unable to join us in 2025, but you're keen to hear about when we launch future events, we recommend you registering your interest here.

Yes, if you've entered and can no longer take part, you are able to cancel your place. As per the terms and conditions of entry, we unfortunately cannot provide a refund or deferral, but we do have a flexible policy, so here's what is available to you: - Firstly, did you purchase the Refund Protect insurance when you entered? If you did you may be able to make a claim - To see everything protected under the policy please click here. - Transfer - you can transfer your entry to someone else, if completed before 30 April 2025. A transfer can be a transfer to someone else or to a different distance (subject to availability). Please see next question for help on transferring your place - If you are unable to transfer, then please email us at info@participationsport.com and you can be entered on to our list to receive a priority entry period and discount to the following year's event. As long as this email is received before 9 May 2025, it will be accepted and you'll be added to our list

Yes, you can transfer your place - either to someone else or to a different distance. Transfers need to be completed before 30 April 2025. A transfer fee will apply and be paid by the person entering. Transfers are only possible if there is capacity remaining in the challenge distance you are transferring to. Full guidelines for transfers here. Transferring to a new Entrant To transfer your entry you will need to log into your MyRaceNation account with the email address that you used to sign up to the event If you've never logged in before click Logging in for the first time , enter the email address you registered with, agree to the T&C and click Claim Account When you have successfully logged in, you will need to locate the entry you wish to transfer and click on the Transfer button. Select Transfer to another entrant You will then be asked to enter the email address of the person you wish to transfer to and select Start transfer. This will automatically send an email invite to the new entrant Once the person you're transferring to receives the email, they must click the Start Your Transfer and complete their details. Please note if the event organiser has applied a transfer fee this will need to be paid for by the person accepting the transfer. When they have completed their registration they will automatically be entered in the event and the original entry will be cancelled. Please note no refunds are processed. Payment will need to be arranged between yourself and the new entrant taking over the entry.