My bad - the revised T&Cs regard paying off other credit cards as Transfers - section B2.2:
Transaction type: Balance transfers
What is it?: Using your available credit to pay some or all of your credit card balance with another UK provider.The minimum transfer is £100.
How do you make it?: By completing the balance transfer request details when you apply for your credit card.You can also ask us to process a balance transfer in branch, by phone or online after we open your account. If there is any other way to process it, we will let you know.
Other important information: If you ask us to process a balance transfer or money transfer, we will transfer the agreed amount when we have completed our security checks, using the Faster Payments Scheme on the working day we approve your request. The money will normally reach the account within 2 hours and no later than the end of the next working day after we receive your instruction.If the other bank or lender is not a member of the Faster Payments Scheme, we may not be able to carry out your request. We are not responsible for this but you can contact us to see if other methods of making the transfer are available.If you make a balance transfer, you should continue to make any payments required by your other lender.If you ask us to make a money transfer or a balance transfer and we send it late, you may ask us to contact the receiving lender and ask them to credit it as if it had been received on the correct date.Section B1 tells you how much of your credit limit you can use to make balance transfers and money transfers.
Cash transactions fall into four categories.
Transaction type: Cash withdrawals
What is it?: Using your available credit to obtain cash.
How do you make it?: Using your card and security details at an ATM or at an over-the-counter service.
Transaction type: Gambling transactions
What is it?: Using your card to make transactions such as those at casinos, betting outlets and bookmakers, and buying online lottery tickets or gaming chips, share trading or spread betting.
How do you make it?: Using your card and security details.
Transaction type: Currency exchange
What is it?: Using your available credit to buy foreign currency at a currency exchange.
How do you make it?: Using your card and security details.
Transaction type: Cash equivalent
What is it?: Using your available credit limit to make cash-related or cash-substitute transactions including:
- sending money orders or wire transfers (other than balance transfers or money transfers)
- buying coins, banknotes or digital currency
- paying government or court fines, enforcement penalties, fees or costs
- online trading such as share dealing or investments
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purchasing or topping up electronic money, payment cards, mobile wallets or account dashboard services.
How do you make it?: Using your card and security details.
All four of these sub-categories have the same detail for Other important information:
Other important information: When you make a cash transaction (including gambling, currency exchange and cash-equivalent transactions):
• we charge interest from the date of the transaction;
• we charge a cash transaction fee; and
• cash withdrawals in a foreign currency also incur a non-sterling transaction fee.
We may treat any transaction at a gambling establishment (e.g. casino) as a gambling transaction, including buying food and drink.
ATMs have a daily cash withdrawal limit of £500 unless the ATM operator sets a lower limit, or we tell you otherwise.
These are the T&Cs for the Platinum and Clarity cards, so may differ for the Cashback card. The salient points for this discussion, I think, I have highlighted in bold.