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2003: British Road Numbering

This puzzle refers to the the system of road numbering in Britain (and yes: I do mean Britain here, not the United Kingdom, as Northern Ireland has a separate scheme which reuses the numbers). The system was apparently developed in the 1920s, and starts with six roads radiating from London, numbered A1 to A6, and another three radiating from Edinburgh, A7 to A9. These roads divide the country into sectors – although it seems that the Thames estuary and the firth of Forth act as dividers in place of the A2 and A7 respectively. All other roads are then given numbers according to their starting point, reckoned as the anti-clockwise end of the road, even if they venture into another sector or sectors. For example, the A46 is so numbered as it starts at Bath, in the “4” sector between the A4 and the A5, even though it extends through the “5” and “6” sectors and ends at Grimsby, in the “1” sector.

The original 1920s scheme has been extensively modified to form the current arrangement of major roads.

Each letter of the alphabet is mapped to one of the major roads A1 to A26, and each road is then represented by its “far” end – the end away from London or Edinburgh, or the most clockwise, as the case may be. For example, Holyhead is the far end of the A5 and so represents the fifth letter of the alphabet, “E”.

The complete code is:

It will be noticed that there are some ambiguities in this code. King’s Lynn is at the far end of both the A10 and the A17 and thus represents both J and Q, but neither of these letters were needed here. Carlisle is at the far end of both the A6 and the A7 and thus represents both F and G; you needed to guess that both occurrences here were Fs. And Dover is the far end of both the A2 and the A20 and thus represents both B and T; both letters were required here, and you needed to interpret these by context. (You probably guessed that I had not changed my name to Trian Tarker.)

The full message is:

Front page

Greenock            Ludborough 
Edinburgh           Scrabster  
 Grimsby           Seaton Burn 
 Grimsby              Dover    
Guildford          Shoeburyness
                   Seaton Burn 

This translates as:

Inside page

 Edinburgh           Shoeburyness
Felixstowe            Scrabster  
 Avonmouth            Eastbourne 

   Dover               Carlisle  
 Holyhead             Ludborough 
Seaton Burn             Hessle   
   Dover             Shoeburyness

 Brighton               Dover    
 Scrabster            Ludborough 
Seaton Burn           Scrabster  
 Greenock             Edinburgh  
 Holyhead             Felixstowe 
Seaton Burn                      
 Carlisle             Edinburgh  
  Hessle              Ludborough 
Ludborough             Norwich   

This translates as:

Once again, I couldn’t resist the cheap air fares to Dublin and spent a couple of days there before Christmas. I timed it right this year, and got there for less than the cost of the fees and taxes. I hadn’t realised when I booked the flights that I should be travelling out on the exact centenary of the Wright brothers’ first powered flight; fortunately, Ryanair managed a bit further off the ground. So the cards were dispatched at the GPO in O’Connell Street – but without Christmas stamps, as there were none for the appropriate international rates. The street scene outside the GPO (on the right in the picture) now has the complete Spire of Dublin (the “Spike”), the first part of which was being erected last year:

Picture of the Spire of Dublin

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Version 14: Revised 11 December 2021
Brian Barker