Love the staff you've got
Job offers may well have whisked your brightest and best from under your nose. While it's too late for any advice about how to retain staff, you might want to consider how you begin to pick up the pieces when important staff leave. For a start, you have to be grown up about it. You've got to shake off that selfish feeling of desertion and be circumspect. After all, perhaps it was your fine influence and training that led your junior member of staff to promotion. (Hopefully you haven't been responsible for driving a single soul out of teaching ... ).
If you've been lucky enough to replace your departing staff, then it is always a happy challenge for middle managers to look forward to inducting new members into the team. Teacher shortage, however, may force the issue of reassessing the calibre of your team. In this instance, the real nitty-gritty is trying to fill the holes of lost expertise. This is when you have to take a long hard look at the staff that remain. You may have no other choice than "to love the staff you've got". Do they have hidden strengths? Is it possible that you have overlooked some characteristics that, with a little fine-tuning, might develop into talent?
The longer I'm in education, the more I realise that adults are just schoolchildren in disguise. Their needs are pretty similar - a desire for encouragement, support, challenge and freedom to develop.
If you apply that to the staff that you lead you might be surprised by the return you get. Sometimes you need to take a risk and put faith in people's ability to grow. Such an approach may not be in your job description, but it's undoubtedly part of any manager's remit.
You may be sorry about your departing staff and regret their decision to leave. But as they say on the mean streets: get over it, move on. You really have no other choice.
Lindy Barclay, Deputy head, Redbridge Community School, Southampton.