Qualified, experienced teachers in some private schools are being paid virtually half what their state-sector colleagues earn.
David Authers, the independent schools' troubleshooter for the Association of Teachers and Lecturers, is dealing with two cases of senior women teachers who are being paid just Pounds 12,500 a year.
Since joining the union five years ago his workload has risen dramatically. Almost every month he hears about another private school that is to close or faces financial difficulties.
The recession has depressed the market and changes in fashion - for example away from boarding schools - have made the business of running a school more precarious and affected the conditions of their staff.
Cathy Moorhouse, an ATL national officer, says she comes across some frightening cases on her beat in the Home Counties. She has dealt with teachers living in rooms which are a fire hazard, women being told they cannot wear trousers or split skirts and contracts which require her members to do anything, within reason (whatever that means), which the head requires.
"Some of the schools, particularly the small ones owned by one person, can be run by a megalomaniac head. Bullying of teachers is a problem in all sorts of schools, but it is worse in the independent sector.
"More worrying is the widespread lack of grievance procedures in these schools. Sick pay terms can be disgraceful and heads often have scant regard to employment law. My concern is that when we hear about problems it is often too late and I suspect they are just the tip of the iceberg."
Mr Authers said many ATL officers find their workload is skewed disproportionately towards independent members because education authorities offer various checks, balances and are more likely to adhere to correct procedures. Teachers in private schools which are feeling the pinch may even offer to take a pay freeze.
But that is not to say all is bleak for potential Paul Pennyfeathers. Salaries in the established and richer schools can outstrip those in the maintained sector. A housemaster in a "top" school can earn in the region of Pounds 30,000. However, as Brian Lane, ATL's officer in the West Country, said, he will have to work very hard for that, possibly being on duty six days a week.
Such schools will expect teaching to be more than a job and for those who enjoy the discipline, the sound of bells and Evensong, and the smell of stewed cabbage and boys' socks, it can be a decent life.
Mr Lane has also seen a number of schools closing in his area. He said: "Independent schools can survive if they are able to react quickly enough to trends and the market. During recessions it can be girls' schools that are particularly vulnerable because parents will tend to put more money into a boy's education."
He believes the recession has changed the nature of many of these schools. To a state-sector teacher struggling with up to 30 children, many with English as a second language, the pupil-teacher ratios in private schools must seem like heaven. "But, when heads are scared to lose pupils - or rather their fees - long gone are the days when parents are ordered to take their child away because of misbehaviour. The boot is definitely on the other foot," said Mr Lane.
It is the one-owner schools and the prep schools which give Ms Moorhouse the greatest concern.
"The prep schools associations have few teeth," she said. "And, many of them expect blood from their staff."