There is a promotion running for free travel on Transport for London services today, plus the next 3 Mondays – if you use a MasterCard with Apple Pay.

Full details on the offer can be found here on the MasterCard website:
http://www.mastercard.co.uk/applepay-fare-free-monday.html

Total refund is capped at £27.90 per card member.

Valid today (23rd November), next Monday (30th) and on the 7th and 14th of December.

EDIT: It also seems that Tesco Bank/Finance have now finally joined Apple Pay, so if you have a Tesco issued MasterCard you can now link it to Apple Pay.
(If you don’t have a Tesco MasterCard, I’m happy to refer (which should earn 1,000 Clubcard points – 2400 Avios. While the earn rate is again not as good as it was, it remains a card free from any annual fee.)