Snap.
I have just spent a few hours dusting the underside of rocks with Ant Killing powder.
Other choice is Nippon Ant killer, they take it back to the nest and it kills the Queen off.

I get ants in my rockery OB I dont tend to do anything and let them be unless they seem to be in the plant roots. Do you think I should OB?

Hmmm. I generally do not bother, except when they are damaging plants. Dianthus are very prone to ant damage for some reason, possibly the acid they secrete, as Dianthus like lime.
The other reason for getting rid of them is our hens, they love to dig up the nests and eat the grubs and eggs, and of course wreck the plants in the process.

Thanks OB