We can’t live without numbers, and everything seems to run on them. Sadly, the records we have for Martins show that although they were first with computers, they never really advanced with the issue of account numbers apart from at the small number of computerised branches. Here, we examine how numbers took over British banking, and quickly took away from us the kind of personal service that involved knowing the customer by NAME…
The National Number
You 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:
		TOWN 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.
The Sorting Code Number
Quite revoluntionary, and like many other clever ideas – quite simple – the humble sorting code has been with us for around fifty years. Similar in use to the national number, the sorting code is a standard length of six digits. 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.
The Account Number
The British banking account number is now almost universally EIGHT digits, although Martins and Lloyds Bank use seven. At the time of merger, Martins numbers will change to eight digits, and will be replaced by Barclays’ eight digit numbers in due course. 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 transmission. 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 be allocated by imposing alphabetical order onto numerical order, as follows:
	The account numbers are printed with the numerical order running upwards – in this case through the rightmost six digits. The first and last digits have been pre-determined to enable the comparison with the branch sorting code to ensure that all numbers are unique to a particular branch. Just as the numbers run upwards in order, they are allocated to account name in alphabetical order. Normally much more space would be left between names, particularly in the case of common surnames 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. Then there is the problem that an account number could appear to be valid on 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 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.
The following letter, reproduced from an original kindly donated to the archive as part of the the W N Townson Bequest, is typical of the Martins’ communication to customers of the tricky concept of account numbers. 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…
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 this point you suddenly become “old friends”…
© gut informiert! 2007 to date