All 22 stations on the Metropolitan Line from Amersham to Liverpool Street have a letter 'R' in their name.
If only Aldgate had an 'R' as well, that'd be the whole journey from one end of the line to the other, but alas not.
Meanwhile there are 18 consecutive stations with a 'T' on the Piccadilly line between Knightsbridge and Heathrow, and 15 consecutive stations with an 'A' on the Metropolitan line between Barbican and Ruislip Manor.
But what really caught my eye was what happens if changes of line are allowed - how many consecutive lettered stations are possible now? To clarify, it's tube stations only, and no station may be visited more than once in each chain.
According to the thread it's possible to travel through 20 successive stations containing the letter 'T', 24 stations with an 'E' and 28 stations with an 'A'. But the winner in this alphabetical challenge is 'R', a letter which they said could be found in the names of 36 successive tube stations from Amersham to North Greenwich. So I thought I'd give this record-breaking 'R' journey a try. And hurrah, I actually managed 38! Here's how.
This route begins almost as far out of London as you can get by tube. Only Chesham would be further, but Chesham doesn't have an 'R' in it, so Amersham it is.
→ CHALFONT & LATIMER → CHORLEYWOOD → RICKMANSWORTH
Technically I could divert via Croxley next, because there are a tiny number of journeys round the North Curve between Rickmansworth and Croxley either very early in the morning or very late at night. But connections would be awkward, and TfL don't bother putting this line on the tube map, so I'm going to ignore the possibility.
→ MOOR PARK
When the Metropolitan line extension is opened in 2020 (or whenever), there'll be a better way to start the 'R' challenge. All the stations from Watford Junction down to Croxley will have an 'R' in, and there'll be five of them, knocking the final total up to 39. In the meantime, however, Amersham is the better way to begin.
→ NORTHWOOD → NORTHWOOD HILLS → PINNER → NORTH HARROW → HARROW-ON-THE-HILL → NORTHWICK PARK → PRESTON ROAD → WEMBLEY PARK
Metropolitan line trains from Amersham used to run fast through a lot of this section, skipping stations to get passengers to central London faster. But these days only a few rush hour services run fast, which means residents of Pinner get more trains but residents of Amersham get slower trains (and stop at lots more stations with an 'R' in).
→ FINCHLEY ROAD
Could a diversion down the Jubilee line have added five more stations? Alas no, because Neasden, Dollis Hill and West Hampstead don't have an 'R' in them, so I had to stay on the Met and speed by.
→ BAKER STREET
Similarly I couldn't take the Jubilee line along this stretch because Swiss Cottage and St John's Wood aren't playing ball. Indeed it's a well known piece of tube trivia that St John's Wood is the only tube station to share no letters with the word 'mackerel', and that's got an 'R' in it.
→ GREAT PORTLAND STREET → EUSTON SQUARE → KING'S CROSS ST PANCRAS
The Metropolitan line continues to Liverpool Street via four more stations with an 'R' in them, but Liverpool Street is surrounded by stations that don't have an 'R' in them so is pretty much a dead end. Instead it's finally time to get off my first train and head for the stations inside the ring of the Circle line. One hour down, one hour to go.
→ RUSSELL SQUARE → HOLBORN → COVENT GARDEN → LEICESTER SQUARE
The Piccadilly line is the only way out from King's Cross St Pancras, because I can't travel via Euston, because it doesn't have an 'R' in it.
→ TOTTENHAM COURT ROAD → GOODGE STREET → WARREN STREET
And now the shenanigans begin. By some fantastic lexicographical quirk, every station inside the Circle line has an 'R' in it (excluding Queensway up one end, and Bank and St Paul's up the other). This reduces the challenge to 'trying to visit as many stations as possible without doing one twice', before exiting the central area at Victoria. Expect a lot of zigzagging.
→ OXFORD CIRCUS
After Oxford Circus and before Green Park, there's a choice of nipping to either Bond Street or Piccadilly Circus - it's not possible to collect both. I chose to take the Bakerloo line because the interchange at Oxford Circus is really easy.
→ PICCADILLY CIRCUS
It'd be nice to pick up Charing Cross by going one more stop down the Bakerloo and coming back up the Northern, but I've already been to Leicester Square, so Charing Cross has to go uncollected.
→ GREEN PARK
And it'd be nice to continue along the Piccadilly line to pick up Hyde Park Corner and Knightsbridge, but South Kensington has other ideas about that, by not having an 'R' in it.
I've now reached the opposite side of the Circle line and grabbed ten stations inbetween, which I believe is the maximum possible, and the key to the challenge.
→ ST JAMES'S PARK → WESTMINSTER
If the first hour on the Metropolitan line was easy, the last 40 minutes spent interchanging around central London has been somewhat of an assault course, and is not for the faint-hearted.
→ WATERLOO → SOUTHWARK → LONDON BRIDGE → BERMONDSEY → CANADA WATER → CANARY WHARF → NORTH GREENWICH
Thankfully the end of the journey is easy, as the Jubilee line delivers seven consecutive stations to finish off the challenge. What is it about the letter 'R' which makes it appear so frequently in the names of tube stations? But it's not possible to continue past North Greenwich as the next stations are Canning Town and West Ham, and they're sadly R-less. Still, that's 38 stations in a row all with the letter 'R' in them, which is pretty damned impressive in itself.
P.S. Yes, I have genuinely travelled this route, and it took me 1 hour and 57 minutes.
P.P.S. If the cable car were part of the tube network, I could then have continued from Greenwich Peninsula to Royal Docks - it's not even necessary to include the name of the sponsor - making 40. And if the DLR were allowed too, I could then have extended my route from Royal Victoria all the way to Gallions Reach, making 47 in total. But that's not allowed, so 38 it is.
P.P.P.S. When Crossrail opens, I think we can get the 'R' total up from 38 to 40 by including a hyperleap between Tottenham Court Road and Bond Street. But in the meantime 38 is the maximum possible, and that's still amazing enough, I think you'll agree.