It's not true in London. Trains delayed by 4 minutes count as late.
There are different times for when you can actually do anything about it - mostly if a train is delayed by an hour you can get a refund (if you chose not to travel) or compensation (if you were already travelling before the delay happened), but it's a bit complicated.
For London tube trains you can get some refunds if the train is 15 minutes late.
> Transport for London (TFL) offers refunds if a passenger's journey is delayed by more than 15 minutes. For tube passengers, this amounts to the fare for the single journey you were making, whether you have a season ticket, or have purchased a single fare. London Overground users get the same, but only when their train is delayed by more than 30 minutes
There are different times for when you can actually do anything about it - mostly if a train is delayed by an hour you can get a refund (if you chose not to travel) or compensation (if you were already travelling before the delay happened), but it's a bit complicated.
For London tube trains you can get some refunds if the train is 15 minutes late.
http://www.theguardian.com/money/2012/dec/18/how-claim-train...
> Transport for London (TFL) offers refunds if a passenger's journey is delayed by more than 15 minutes. For tube passengers, this amounts to the fare for the single journey you were making, whether you have a season ticket, or have purchased a single fare. London Overground users get the same, but only when their train is delayed by more than 30 minutes