Positively the last instalment in this saga (at least for today).
If we count Hammersmith and Paddington as each consisting of two separate stations (since in each case the Hammersmith and City Line serves a separate station from the District Line) then we can construct a circular route using no less than 108 stations as follows:
Hammersmith (District/Piccadilly), Barons Court, West Kensington, Earl’s Court, High Street Kensington, Gloucester Road, South Kensington, Knightsbridge, Hyde Park Corner, Green Park, Piccadilly Circus, Charing Cross, Leicester Square, Covent Garden, Holborn, Chancery Lane, St Paul’s, Bank, Monument, Cannon Street, Mansion House, Blackfriars, Temple, Embankment, Westminster, St James’s Park, Victoria, Pimlico, Vauxhall, Stockwell, Oval, Kennington, Elephant & Castle, Lambeth North, Waterloo, Southwark, London Bridge, Bermondsey, Canada Water, Canary Wharf, North Greenwich, Canning Town, West Ham, Bromley-by-Bow, Bow Road, Mile End, Stepney Green, Whitechapel, Aldgate East, Tower Hill, Aldgate, Liverpool Street, Moorgate, Barbican, Farringdon, King’s Cross St Pancras, Euston, Warren Street, Goodge Street, Tottenham Court Road, Oxford Circus, Bond Street, Marble Arch, Lancaster Gate, Queensway, Notting Hill Gate, Holland Park, Shepherd’s Bush, White City, East Acton, North Acton, West Acton, Ealing Broadway, Ealing Common, North Ealing, Park Royal, Alperton, Sudbury Town, Sudbury Hill, South Harrow,.Rayners Lane, West Harrow, Harrow-on-the-Hill, Northwick Park, Preston Road, Wembley Park, Neasden, Dollis Hill, Willesden Green, Kilburn, West Hampstead, Finchley Road, Swiss Cottage, St John’s Wood, Baker Street, Marylebone, Edgware Road (Bakerloo), Paddington (Bakerloo/Circle/District), Edgware Road (Circle/District/Hammersmith & City), Paddington (Circle/Hammersmith & City), Royal Oak, Westbourne Park, Ladbroke Grove, Latimer Road, Wood Lane, Shepherd’s Bush Market, Goldhawk Road, Hammersmith (Circle/Hammersmith & City). We then complete the circuit by interchanging back to our starting point.
This tour travels from one Hammersmith station to the other, without calling at any station twice or even leaving the system, in 106 stops (plus the interchange from Monument to Bank), making 108 stations in all (including the starting point).
And if we don’t want to restrict ourselves to circular routes, we can make an Underground journey that uses no less than 137 stations without any repetition, by starting at Epping and travelling via Woodford and Hainault to Mile End, where we pick up the circuit shown above and follow it almost all the way round as far as West Ham, before finally proceeding to Upminster. In doing so we would visit more than half the 270 stations on the London Underground system.