I trimmed and sprayed as necessary then Footvaxed in 2007. Moved them onto ground that hadn't been grazed for three weeks, then moved them onto clean grazing again. Not seen it (or had to vaccinate) since. No scald either. I run a virtually closed flock and quarantine incoming rams on my neighbour's smallholding for six weeks before they join the flock. The vaccination was expensive but I must have saved the cost in the purple foot spray I didn't need in the following year, let alone since. Only thing I'd do differently would be to jab in the Autumn. The adjuvant is very thick and the young ewes rubbed and rubbed the injection spot against fences until it was raw so we had to gather them and spray to keep the flies off every few days for a few weeks.