The content blade requires the following to match for a UK IBAN number in a close proximity.
European IBAN number format
UK IBAN number pattern
IBAN Rule: "GB" country code followed by 20 characters.
GB, ISO country code
2 Digits (numeric characters 0 to 9 only) , Check Digits (IBAN)
4 Upper case letters (A-Z only), Bank Identifier Digits
6 Digits (numeric characters 0 to 9 only), Bank branch code
8 Digits (numeric characters 0 to 9 only), Account number
Pattern:
GBDDLLLLDDDDDDDDDDDDDD
GB DD LLLL DDDD DDDD DDDD DD
GB DD LLLL DDDDDD DDDDDDDD