Do I need my phone to be present when using debit/credit cards stored on my watch

Hi

No - once payment cards have been added to Apple Pay on your watch, your watch can be used to make payments via Apple Pay entirely independently of your iPhone.

Check that you are presenting your watch to the payment terminal correctly.

To use Apple Pay, quickly double-press the side button. Your default card will be displayed. If you have added other cards and wish to use one of those instead, swipe to switch between cards.

With your preferred card selected, when holding your watch up to the terminal:

• The watch face should be facing and parallel with the terminal's own screen (you should not be able to see the watch face whilst paying), aligned centrally with the contactless logo on the terminal screen and held closer than 1 inch.
• It should be held in that position for up to a few seconds, until you hear the confirmation beep and haptic pulse.

In the UK, you may be unable to use Apple Pay in some stores for sums over £30 (currently a common limit for contactless payments).

More information:

Using Apple Pay in stores and within apps - Apple Support

If you followed all of the steps correctly, you may wish to contact your bank, who may be able to advise why the transaction was not authorised.

You can also report your failed transaction to Apple here:

https://www.apple.com/feedback/apple-pay.html

The feedback form enables you to report any problems that you encounter with specific merchants, transactions and payment cards, so can be helpful in enabling Apple to identity and investigate any issues.