London Underground has nice clear policies around this, both about what you'll be charged https://tfl.gov.uk/fares/how-to-pay-and-where-to-buy-tickets-and-oyst

London Underground has nice clear policies around this, both about what you'll be charged https://tfl.gov.uk/fares/how-to-pay-and-where-to-buy-tickets-and-oyster/pay-as-you-go/touching-in-and-out#on-this-page-5 https://tfl.gov.uk/fares/how-to-pay-and-where-to-buy-tickets... And about refunds (typically you'd get an automatic refund for a one-off event) https://tfl.gov.uk/fares/refunds-and-replacements/touched-in-and-out-at-same-station https://tfl.gov.uk/fares/refunds-and-replacements/touched-in... I always have high levels of respect for companies with such clarity