Cats and nest boxes

Hi,

We have great tits nesting in a box in our garden.  Unfortunately, I've sited it incorrectly and a neighbours cat has been caught on our webcam putting a paw into the box.

I don't want to add a nestbox guardian to the box for fear of disturbing the birds.  Shall I add rose cuttings around the top of the box and underneath to deter the cat or should we try to fix the guardian or fix chickenwire to the front?

I guess we should probably leave well alone and then resite the box next year - perhaps adding rose cuttings  to the top of the box and underneath to deter the cat?

Any advice appreciated.

Thanks.

Rosemarie