Hi craggentoul, you can record this by following the steps below to create an expense to the supplier:
1) Select +New > Expense
2) Select the Supplier under Payee, the account the BACS payment was made from under Payment account, and the date that this was paid
3) Set the Amounts are drop-down to No VAT
4) On the Category details line, set the Category to Creditors (or Accounts Payable) then enter the amount and save
This will then post as an unapplied payment on the supplier's account, which can then be applied to a future open bill by selecting Make payment on the bill > Tick the expense under 'Credits' on the following screen. :woman_technologist:
Thanks!