A bit more on this topic. Justin (whose book is coming out soon) shared some figures with me in an e-mail. Over the period 1990-2006 the average number of clergy leaving the ministry each year, for various reasons, was:
Death in post: 24
'Other losses': 258
That's out of a total clergy number of around 9,000 average, so around 3% of clergy leave the ministry each year. I wonder how that compares with other professions? I wonder also whether a vocational ministry might not expect a lower rate of departure compared to other professions (after all, there's more at stake in priest leaving ministry than, say, an accountant joining a non-accountancy company). Unfortunately the CofE doesn't keep figures on _why_ clergy leave the job.
It's been on my mind again, partly for personal reasons (like discovering the other day that if I'd stayed in the civil service I'd be earning around £70k now, on a conservative estimate!), and partly because Tim put up an interesting post relating to it (see my comments in the thread).