It’s the most popular race on the planet and, for those lucky enough to have a place, the final countdown is officially on. But what can’t runners do at the London Marathon? From running with your dog, to turning up late, here’s 12 things you absolutely cannot do if you’ve got a place at the London Marathon.

1.Swap your running number

It might sound obvious, but if you run using someone else’s number, let someone else run with yours, or make a counterfeit number, you could be banned from all further London Marathon events for up to five years. London Marathon organisers explain that, 'number swapping is strictly prohibited for a number of reasons, the most important of which is the danger and confusion it can cause in the event of an incident on the course.' If you're taken ill on the course, your number is used to contact your family, so swapping numbers can cause distress to family members and waste emergency staff time.

2. Apply for a Good for Age place using someone else's time

Participants will also be banned from all future events organised by London Marathon if they apply for a Good for Age place using someone else’s times, or falsify information on your own entry form.

3. Go for a wee in public

Runners should not urinate in any front gardens or public places along the 26.2 mile course, but should always use the portaloos provided.

4. Take water from every station

London Marathon is encouraging runners to wear bottle belts this year to reduce crowding, as well as plastic waste. There will still be water stations and, of course, people should listen to their bodies and drink when thirsty, but event organisers are encouraging participants to adopt a 'bottle balance'. Plus, over-hydrating also has its own risks, so think carefully about your hydration strategy.

5. Drop full bottles of water in the middle of the road

Not only can this be dangerous to fellow runners, who can easily trip on a water bottle, but plastic water bottles with liquid in cannot be recycled, so runners are encouraged to squeeze out remaining liquid in the bottle, before discarding them to the side of the road.

6. Wear a jumper over your running number

Make sure your running number is correctly secured and isn’t covered, as London Marathon organisers won’t be able to identify you in your race photos and runners without numbers will be removed from the course.

7. Be late to your Assembly Area

This year, runners will set off in waves over a one-and-a-half hour period to reduce crowding at the Start. Your registration email contains details of your start wave and arrival time, which you can also find via the London Marathon 2021 app.

If you fail to arrive to the start location of the marathon at the specified time, London Marathon organisers reserve the right to refuse entry to the race. In other words, plan your route and leave plenty of time for public transport to go wrong.

8. Have a pre-run pint

London Marathon organisers have the right to refuse your entry into the race if they feel you are unable to participate due to the consumption or use of alcohol or drugs. Save that pint for the finish line, and check out the best places to get free food and drink with your finishers medal here.

9. Bring your dog (or any pet) with you

You are not permitted to bring any pets or animals with you to the London Marathon, or use them to help you along the course.

10. Run in new shoes, or a costume you haven’t practised in

It might sound like an obvious one, but London Marathon organisers remind all runners not to run in brand new shoes on race day, or wear a fancy dress costume they have not trained in.

11. Bring more than one spectator

This year, participants are being asked to invite only one supporter to come along and watch in person, as a COVID-19 safety precaution. Spectators are asked to avoid gathering in large numbers, and if an area is busy, to find another place to watch the event. Stewards will ask spectators to move on if areas become crowded.

12. Apply for next year’s ballot under multiple email addresses

If you’re inspired by this year’s race, no matter how much you want to run, participants cannot enter the ballot more than once using different email addresses. Participants who do this can be banned from all future events organised by London Marathon for a period of up to five years.