My latest numberplate-spottinggame is trying to spot all the pairs of letters at the start of a vehicle registration plate.
AA AB AC AD AE AF AG AH AJ AK AL AM AN AO AP...
BA BB BC BD BE BF BG BH BJ BK...
CA CB...
...
........YJ YK YL YM YN YO YP YR YS YT YU YV YW YX YY
There are a heck of a lot of them.
You might expect there to be 26×26 = 676 possible combinations, but the letters I, Q and Z are never used (for alphanumeric confusion reasons) which shrinks the list to 23×23 = 529.
n.b. My game is specifically about the first two letters at the start of modern numberplates - the 'memory tag' - not the subsequent two digits nor the three random letters on the end, so I won't be going into any of that.
The first letter in each pair represents the geographical area in which the plate was registered, so for example A is for vehicles originating in (East) Anglia, B for Birmingham and C for Cymru, i.e. Wales. This regional list was introduced in September 2001 when the current system of rationalising numberplates began. If you're not familiar with it after the best part of quarter of a century, here's my attempt at a map showing the approximate regions and their designated letters.
Some of the regional names are both obvious and appropriate. E for Essex, L for London, S for Scotland, Y for Yorkshire, perfect. M for Merseyside and Manchester, very clever. Using C for Cymru allowed them to use W for West of England, for which well done.
Other regions have less familiar names, for example the somewhat artificial 'Deeside to Shrewsbury' and the frankly weird 'Forest and Fens'. Preston might have been better as 'Lancashire and the Lakes', but London had of course already taken L.
The strangest omission is region K, the approximate M1 corridor from Herts to Northampton, which civil servants failed to give a name. Personally I'd have given K to Kent, specifically 'Kent and Sussex' rather than the twee 'Garden of England', but all this is water under the bridge because these letters were fixed at the start of the century and are now plastered across millions of numberplates.
n.b. You'll see that the letters J, T, U and X aren't used, regionally speaking. But the DVLA still issue them on personalised numberplates, should you be willing to stump up for the novelty, so all the pairs from JA to XY remain in the game.
The second letter in the pair may also be geographically based, relating to the specific DLVA Local Office issuing the plate. For example, in the Anglia region AA-AN was used for cars registered at Peterborough, AO-AU at Norwich and AV-AY at Ipswich. The most complex set-up was in Scotland with SA-SJ for Glasgow, SK-SO for Edinburgh, SP-ST for Dundee, SU-SW for Aberdeen and SX and SY for Inverness. But several regions weren't similarly subdivided, specifically B, E, M, O, R and V where the second letter offers no further clues.
You can see the official list on page 5 of this official guide issued by the DVLA, or if you don't like pdfs here's a jpeg and here's the relevant Wikipedia page. The BBC news website published the full list in an article as long ago as August 2001, so there really is no excuse for ignorance.
Also, if you look at these lists carefully you'll see that three pairs of letters haven't been issued. FO and FU are banned, for sweary reasons, so you won't see cars with that opening combination anywhere in Great Britain. The other blacklisted pair is NF, for fascist reasons, and rightly so. The only other totally-unused pair is MN, which has long been reserved for the Isle of Man but the IoM has never taken up the DVLA's kind offer.
Removing these four from the list of combinations means there are 529-4 = 525 possible numberplate starters. And yes, the game I've been playing is trying to spot them all.
It's a particularly silly game, indeed initially overwhelming because almost every car going past ticks another pair off the list. I took it gradually, starting out by just focusing on As and Bs, then introduced additional letters on subsequent days. Eventually you're only looking for a small number of missing pairs for each starting letter and things get more manageable, but it remains a ridiculously complex task of memory and observation.
Also it takes ages. I started at the beginning of December and I still haven't finished, ten weeks later.
By the end of December I'd seen 433 different pairs, i.e. I had 92 still to go. By the end of January I was up to 486, i.e. still 39 short. The game gets a lot slower the longer it continues because there are fewer remaining pairs to spot, plus by definition they're the rarest ones to see. I'm currently on 489, i.e. I've only seen three more since the start of the month because that's how rare some of these pairs are. At this rate I could be playing for some considerable time.
I'll come back tomorrow and tell you what I've learned about the distribution of letter pairs on GB numberplates, because playing the game has confirmed that some are considerably less common than others.
In the meantime if you'd like to play a much-simplified version of the game and experience what I'm talking about, have a go at this.
These are all the possible letter pairs at the start of a numberplate issued in London. While you're out and about in the capital today, see how many of them you can cross off.
It won't take you long to spot the majority of them, maybe ten minutes on a typical street with passing traffic. Numberplates starting with L are really commonplace in London, perhaps a quarter of all the vehicles you'll see, so you should make good progress really quickly. My experience suggests you'll have the entire third and fourth rows crossed off before too long.
But on the other rows some of the letter pairs are more infrequent so expect to retain some gaps for a while, and one or two are really stubborn so you'll likely not spot them at all. Have a go and you'll soon start to uncover the mysterious underlying world of numberplate letter pair distribution, and this'll be the subject of tomorrow's post.
n.b. If you don't live in or near London don't try using Ls, pick a letter more local to you, but in this case I can't guarantee how easy the game will be.
