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We can’t live without numbers, and everything we use seems either to run on them, or consume them in the form of money!  Sadly, although Martins is the first benk to regularly process branch daily work on a computer, they never really advance very far with the issue of account numbers apart from at the small number of computerised branches. Boffins at the LONDON COMPUTER CENTRE and LONDON AUTOMATION begin to put the work of London Branches onto the mainframe. Work is also in hand to connect London and Liverpool by landline.  In 1966 Martins seven digit account numbers are changed to an eight digit system as part of an ambitious computerisation of London Branches. After the merger with Barclays,  Martins computerisation is largely absorbed into “Project Burroughs” a mammoth task designed to put every branch in the country online.  The notable exception is Martins computer program “Branch Accounting” many aspects of which are retained by Barclays.


Here, we examine how numbers take over British banking, and also quickly take away from us the kind of personal service that involves knowing the customer by his or her face, and most importantly by NAME…

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The National Number

Cheque Montage.jpgYou will note from the cheques on the right, that some have the familiar three pairs of numbers printed at the top right corner, known as the Sorting Code.  This method of identifying banks and their branches is still used today, although the number of branches of every UK bank has decreased dramatically since the sorting was introduced in the 1960s. Before the Sorting Code, and the encoding of it and other details in MAGNETIC INK along the bottom of cheques was used, banks were known by their NATIONAL NUMBER.  The five digit National Number works in a similar way, in that the first one or two numbers represent the bank, and the remaining digits represent the branch of that bank. Under both systems, the bank number for Martins is 11.  With National Numbers, branches are actually numbered in order of importance:

NNLM1TOWN CLEARING BRANCHES  are a number of the more elite London Branches and bear only one digit after the 11. e.g. 111


METROPOLITAN BRANCHES cover Greater London and consist of two digits after the 11. e.g. 1124


COUNTRY BRANCHES make up the rest of the country, and bear three digits after the 11. e.g. 11056. Martins Branches in the Channel Islands and Isle of Man are allotted a range of special numbers between 79001- and 79199. In the examples on the left, the Bank Number for Lloyds is 3, and 4, for Midland Bank.  When Sorting Code Numbers arrive, the bank numbers will be changed slightly, to 30 and 40.

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The Sorting Code Number and the Account Number…

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Quite revoluntionary – not least because of its simplicity – the humble sorting code has been with us for around sixty years.   Similar in use to the national number, the sorting code uses a standard length of six digits for every bank branch. This departs from national numbers because no longer can an elite town or city branch be recognised as such by just three numbers, everyone has six. The purpose of this relates to the security apsect of account   The first two always denote the Bank – 11 Martins,  20  Barclays and so on.  The remaining four figures denote the branch or department of the bank that will use that particular unique code number.   

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The British bank account number is nowadays almost universally EIGHT digits, although Martins uses seven until merging with Barclays, and Lloyds Bank uses seven until is takes over the TSB in 1991. At the time of Barclays merger, Martins numbers will change to temporary eight digit account numbers, and later be replaced by Barclays’ eight digit numbers.  Now comes the clever bit.  All bank computers run a special algorithm that performs a calculation against both the sorting code and the account number.  The outcome of the calculation determines whether an account number is correct and issued for use with a particular sorting code.  Each account number contains a common set of digits, which usually advance numerically upwards, and one or two digits which are used to compare the number against the sorting code of the branch.  The branch computer checks the account number on input, and the mainframe computer checks it again on receipt.


Before the advent of the more powerful banking computers, account numbers are issued from printed books (valid number books) which in theory contain far more account numbers than any branch is ever likely to need – therefore even the major branches with thousands of accounts should never run out.  Some banks will continue to issue account numbers in this way until the early 1990s.  The numbers are allocated by imposing alphabetical order onto numerical order, as follows:


·         The account numbers are printed with the numerical order running upwards in value – in this case through the rightmost six digits. 

·         The first and last digits have been pre-determined to enable the computer to compare them with the branch sorting code to ensure that the account number “belongs” to a particular branch.


·         At this point in the development of computerised accounting, the programming skills and memory capabilities are just not able to have every account sorted into alphabetical order each day by the computer.

·         So, a simple but clever method is devised to enable accounts to remain in alphatical order for the benfit of staff looking at lists and reports, but also to remain in NUMERICAL order to allow the computer to work more efficiently and quickly: Just as the account numbers run upwards in value, they are allocated to account name upwards in both numerical AND alphabetical order.  Our example simplifies this procedure for presentation – Normally much more space would be left between names, particularly in the case of common surnames such as “Smith” for which there might be a large number of accounts held.

Some banks use what are known as different “ranges” of account number.  This is achieved by splitting the continuous run of numbers into different sections, using each section for a different account type, and enabling the production of several alphabetical lists of customers by type of account. It would be extremely difficult to produce enough account numbers for every bank account in the country to have its own unique number, but this presents the problem that an account number could appear to be valid for more than one sorting code.  This problem is largely and quite cleverly overcome by ensuring that sorting code numbers are themselves allocated so as to avoid neighbouring branches’ account numbers being interchangeable.  It’s a bit like the way neighbouring analogue radio and TV transmitters used to have to operate on different frequencies to avoid interference.  The last thing a customer would want is for someone with an identical account number to be able to access THEIR funds, and although this type of error can occur, it is kept to a “manageable minimum” by the careful distribution of sorting codes.  This in turn enables the number of different valid number books to be published, to be kept to ten. Thus there are ten versions of every account number, and each begins with one of the ten digits 0 to 9. These numbers can be used many times over across a network of branches, on the basis (in theory) that the same number does not crop up twice in the same geographical area.

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The letter shown here was used by Martins Bank in 1968 to communicate to customers of 68 Lombard Street Branch that their accounts were to be given numbers.  It was accompanied by the leaflet “Computers and Your Account”.  You can tell by the language used in the letter, that the Bank is all too aware of how contentious this issue of account numbers is for customers, and that some careful “tiptoeing” is required so as not to upset those with large amounts of money in their bank accounts - Back then, it was the bank that served the customer, a far cry from the twenty-first century, where if you don’t like what your bank is doing, they will be happy to see you go somewhere else, rather than accommodate your needs! Where previously all that was required of you by your bank was your name, you are now to be known also by your number.  This does not of course, not go down well with everyone, and customers claiming they do not know or even have any idea where to find their account number, is something bank cashiers have to put up with for DECADES to come!

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That’s probably quite enough about numbers for now, save to note with some sadness that it is these innocent strings of quite cleverly arranged digits that are instrumental in replacing the cashier’s personal knowledge of the customer, and will bring about today’s delay in recognition of you, by many bank staff until the moment your details appear on the screen in front of them.  At which point, suddenly, they seem to know everything about you…