If you've paid for something on a card but since cancelled it, you may still have Section 75 protection.
The Financial Ombudsman Service told us that assuming you meet all other criteria you should be covered, as the fact you've cancelled the card doesn't matter. The original payment method is what's important – in other words, that you paid on a credit card.
If you have any doubt, put in a claim – the worst that can happen is your claim is rejected.