Denmark Hill, Elephant & Castle, London Blackfriars, City Thameslink, Farringdon, London St Pancras (Intl), Kentish Town, West Hampstead Thameslink, Cricklewood, Brent Cross West, Hendon, Mill Hill Broadway, Elstree & Borehamwood, Radlett, St Albans, Harpenden, Luton Airport Parkway, Luton