Mizter T (Mizter T ) gurgled happily, sounding much
like they were saying:

Yes again- having spoken to somebody who works in the fraud risk
department of a bank, the UK is only just moving to a system of having
the same number of digits in a debit card number as the rest of the
world. Prior to that it wasn't possible to use a UK-issued debit card
for online transactions processed abroad as foreign systems wouldn't
accept our account numbers.

I think the issue you're referring to on concerns Switch debit cards,
which have now been rebranded Maestro, which used a different numbering
system but I believe are now 'switching over' to the worldwide standard
(16 principal digits).

It's going to be a while yet until that's complete...
looks at own Maestro (not Switch) card
Expires late 2010, 18 digits.

The long digit, in my card's case at least, is just the four-digit issuer
prefix, then the sort code and account number...

Trivia time - it's easy to identify a card type by the first digit.
3-Amex/Diners/JCB, 4-Visa, 5-Mastercard, 6-Maestro.