Turns out I do have sub-clinical levels of cocci, so this was a very useful thread, thanks!
Nobody scouring, all lambs gaining weight. The vet agreed that this is unusual in outdoor flocks to see the counts that I have, so I'm putting it down to the weather. I have ordered some cocci buckets as I'm buggered if I'm paying for vecoxan when cocci are at a subclinical level. I'll have another count done in a few weeks and se how well they work.