In this earlier piece I asked the following question, regarding the names of stations on the London Underground: What is the smallest number of stations that you would need to make sure that all 26 letters of the alphabet are included at least once? The question arose from the answer to my favourite trivia question: What is the only station on the London Underground that contains the letter Z?

I have used a spreadsheet containing all 269 station names to analyse how often individual letters appear and it looks like you need at least 6 stations to cover all 26 letters of the alphabet. My solution incorporates 6 stations, 8 words, 60 characters (or 62 characters including spaces). If it can be done in fewer words or characters please show me how.

My solution

The 6 stations that I use are: Belsize Park, Willesden Junction, Vauxhall, Queensway, Greenford, Temple

That gives us 6 stations, 8 words, 60 characters (or 67 characters including spaces)

Here are some of the steps I used to get there.

First, here’s a list of rare letter stations, with the letter of the alphabet, the number of stations, and the station names:

Z: 1, Belsize Park

J: 3, St. James’s Park, St. John’s Wood, Willesden Junction

X: 5, Brixton, Croxley, Oxford Circus, Uxbridge, Vauxhall

Q: 7, Euston Square, Leicester Square, Queen’s Park, Queensbury, Queensway, Russell Square, Sloane Square

V: 13, Vauxhall, Arnos Grove, Covent Garden, Ladbroke Grove, Liverpool Street, Maida Vale, Oval, Perivale, Ravenscourt Park, Roding Valley, Seven Sisters, Victoria, Warwick Avenue

You have to include Belsize Park, and that gives you 10 different letters: ABEIKLPRSZ

Willesden Junction gives you a further 8 letters CDJNOTUW

This leaves you with 8 letters still to find: FGHMQVXY

Vauxhall gives you V, H and X

Queensway gives you Q and Y

This leaves you with the letters MGF: no station has all 3 letters but there are various ways to get them in 2 station names. I can’t find any solution that uses fewer than 15 characters, and have opted for Greenford and Temple rather than Moorgate and Fairlop (both use 15 characters).