Gatwick Express has been told to stop claiming its trains get to Victoria "in just 30 minutes" in adverts - unless it can actually achieve that journey time in most cases.
The Advertising Standards Authority (ASA) has upheld a complaint about Gatwick Express's website and one of its posters, which claimed the company offered a service which travelled "non-stop to Victoria station in half an hour", and that the service would get you to Victoria "in just 30 minutes".
But the ASA found that 20.1% of Gatwick Express trains between London Victoria and Gatwick Airport were delayed between 30 April and 26 May, and has told it that the adverts mustn't appear again in their current form.
Gatwick Express fares to Victoria start from £14.50 but it's possible to get to the airport for less using different routes, check out our London MoneySaving guide for the full information.
For how to claim if your train is late or cancelled, see Train Delays.
What does the ruling say?
Gatwick Express said a total of 79.1% of scheduled trains between Victoria and Gatwick arrived at their final destination on time between 30 April and 26 May, and it said trains were late the rest of the time because of engineering work, signal failures or unavoidable incidents such as a passenger falling ill.
It also argued that it was difficult to mitigate against certain causes of delays such as staff sickness, and said any driver involved in an operational incident had to take a set amount of time off work.
But the ASA ruled that the ads must not appear again, adding: "We told Gatwick Express to remove the claims 'Non-stop to Victoria station in half an hour' and 'in just 30 minutes' unless they could achieve that journey time in most cases, save for exceptional and unforeseeable circumstances outside of Gatwick Express's control."
If my train is delayed, can I claim?
You can claim Delay Repay compensation if you're on a delayed Gatwick Express service and arrive at your destination more than 15 minutes late.
Full details on how to claim can be found here.
What does Gatwick Express say?
A Gatwick Express spokesperson said: "Just a third of Gatwick Express delay minutes were within our control, however we acknowledge the ASA ruling and began withdrawing these adverts many months ago."