Do you have any of your old emails from them as it includes your identifier at the bottom? If not you could try send a small amount to one of the addresses if you had email notifications turned on as it'll send you an email notifying you of the payment.
[...] I don't think there
was an email linked to it, it's quite old and I don't even think it asked for an email back then.
@OP: If you are unsure whether you have linked your email with Blockchain.info or not, you should do as hilariousandco said. You maybe lucky!
P.S. Check "sent" & "draft" folder in your email account. It is possible for you to sent Blockchain.info support your identifier if have you contacted them.