Elstree & Borehamwood – Kew Gardens via West Hampstead is charged as a Zone 2-6 journey on the “Mixed Mode” scale so would be £5.30 Peak / £3.70 Off-Peak on Contactless/Oyster and £6.10 Single / £11.90 Return for Cash.
West Hampstead – Kew Gardens, meanwhile, is charged as a Zone 2-3 journey at the TfL rate, thus £1.90 Off-Peak / £2.10 Peak on Contactless/Oyster but attracting the non-PAYG premium charge of £6.70 Single for Cash.