There's a few styles of Carradice front panniers and even the same models have had a variety of fixings over the years so there may be an answer ideal to yours that will be missed without knowing the specifics.
On several panniers and racks, I've followed the advice as above, first as in4 says make sure the panniers have minimal movement on the rack, then like Andyb1 some tape to build the rack up a bit, which also protects it. Any tape will do, within reason, it doesn't have to last a lifetime, it's a quick job to replace it when it gets scruffy. I've used insulation tape and duct tape in the past, both were fine. I now have some helicopter tape which is even better, I had a bit left over from some frame protecting, I wouldn't have bought it specifically.
If they're still rattling, or you're doing a lot of rough-stuff, or you just want more security, you can add more hooks. If your fitting system is the one with aluminium channel it's easy to add hooks or the securing clips:
https://carradice.co.uk/collections/accessories?page=1