This puzzle referred to the well-known London Underground diagram, a copy of the pocket version of which was enclosed with the card. Each station represented a letter or digit within a word, and each vertical list of stations a word in the message. The puzzle was to find the correspondence. The diagram has squares used for indexing the stations; each station represented the square in which it featured on the diagram, with thirty-six of these squares representing the letters of the alphabet and the digits in a simple fashion, starting in the top-left corner of the diagram:
1 2 3 4 5 6 7 8 9 A A B C D E F G H I B J K L M N O P Q R C S T U V W X Y Z 0 D 1 2 3 4 5 6 7 8 9 E F
For example, Mornington Crescent is in square B5 on the diagram, which represented the letter “N” and so on.
It is worth noting that the correspondence between stations and index squares was that for the then-current version of the diagram, which differs from later ones. Recipients who are not familiar with the London Underground (and even some who are) may be surprised to know that the diagram is changed quite frequently. Apart from more obvious changes such as the extensions to the Jubilee Line, the Docklands Light Railway, and the Heathrow end of the Piccadilly Line, the transfer of some National Rail lines to the London Overground and to TfL Rail, and the addition of London Trams, there are small changes, such as to station names or interchange patterns or for temporary closures, which require modifications of the diagram typically a few times a year.
The full message was:
Front page
Harrow & Wealdstone
Loughton
Buckhurst Hill Newbury Park
Chalfont & Latimer Theydon Bois
Finsbury Park Hanger Lane
Highbury & Islington Park Royal
Stepney Green St John’s Wood
Ruislip Manor
Ealing Broadway
This translates as:
Buckhurst Hill A8 H
Chalfont & Latimer A1 A
Finsbury Park B7 P
Highbury & Islington B7 P
Stepney Green C7 Y
Harrow & Wealdstone A3 C
Loughton A8 H
Newbury Park B9 R
Theydon Bois A9 I
Hanger Lane C1 S
Park Royal C2 T
St John’s Wood B4 M
Ruislip Manor A1 A
Ealing Broadway C1 S
Inside page
Boston Manor
West Ruislip Cyprus
Belsize Park Prince Regent
Hendon Central Canada Water
North Harrow Finchley Central
Mill Hill East Elm Park
Ealing Broadway Caledonian Road
Alperton West Hampstead
Great Portland Street Northwood Hills
Grange Hill Barkingside
Hanger Lane Roding Valley
Woodford Chorleywood
Hampstead Mornington Crescent
Ealing Broadway
Moor Park
Totteridge & Whetstone Chesham
Tufnell Park Gants Hill
Dagenham East Harrow-on-the-Hill
Mill Hill East
Upminster Bridge
This translates as:
West Ruislip A1 A
Belsize Park B5 N
Hendon Central A4 D
North Harrow A2 B
Mill Hill East A5 E
Ealing Broadway C1 S
Alperton C2 T
Great Portland Street C5 W
Grange Hill A9 I
Hanger Lane C1 S
Woodford A8 H
Hampstead A5 E
Ealing Broadway C1 S
Totteridge & Whetstone A6 F
Tufnell Park B6 O
Dagenham East B9 R
Boston Manor D1 1
Cyprus D9 9
Prince Regent D9 9
Canada Water D7 7
Finchley Central A6 F
Elm Park B9 R
Caledonian Road B6 O
West Hampstead B4 M
Northwood Hills A2 B
Barkingside B9 R
Roding Valley A9 I
Chorleywood A1 A
Mornington Crescent B5 N
Moor Park A2 B
Chesham A1 A
Gants Hill B9 R
Harrow-on-the-Hill B2 K
Mill Hill East A5 E
Upminster Bridge B9 R
Version 28: Revised 13 December 2020
Brian Barker