I understand that some Water Regulations stipulate that on a hosepipe connection to any tap you must have a non-return valve to prevent back flow and water contamination.
This is anecdotal only, I don't have any hard evidence to back it up - perhaps The Builder or other professional would know.
As you can see the mixer tap hasn't got much of a vertical lip - so would webbo3 suggestion work - or would I need an adaptor that connects horizontally ?
The tap in this video appears to very similar to yours. The adapter has a different number but looks the same as the one recommended.
https://youtu.be/EHt_SRhqF-U