She turned to her local authority's education personnel department for advice. Officers took her through the authority's competence procedure and suggested that she start monitoring Brian's work closely and keeping notes.
It was not easy. Brian had almost 20 years' experience and believed he was doing a good job. His union became involved and the situation grew increasingly fraught.
Eventually Anne decided to start competence proceedings. Brian was offered support and given eight weeks to improve. There were some improvements and the proceedings, which had not reached the formal warning stage, were stopped.
With a local authority prepared to give her practical support, and backing from the National Association of Head Teachers, Anne was luckier than many heads who find themselves in a similar position. But her determination not to tell other staff what was going on left her feeling isolated. She describes the year when these events took place as one of the worst of her life.
"It was a very great strain," she says. "The worst part was confronting the teacher. I had to watch what I said, how I said it and when I said it. I'd had very little training in any of this and I'm not a person who likes confrontation."