The first job out of my time in 1986, I earned £8.50 an hour as a 715 working subcontract to a builder. Started pricing for jobs (1980s) and earned £200 a day doing lead-work, at that time you could buy a decent house for about 15k. I did a twenty years stint where customers had to wait on average 3months for a heating installation. My average wage during this time was about 25K a year, for a 40 hour week. Of course you never did a 40 hour week in the past, because there was loads of work, it was more like 50-60 hours a week. Hence plumbers could earn more through working longer hours - this explains the 'rich plumber' tag. Those that have it, have worked hard to get it.
From then to present my wages have fallen drastically, along with continuity of employment. Over-heads have crept up in price - cost of vans, insurance and courses for ACS and gas registration. As work diminishes, advertising and marketing creep up.
In addition, the public have lost trust, and now expect me to come out for nothing, or no call out - which is ridiculus. If a job goes wrong, then customers lose trust - in the past they were more reasonable, and expected jobs to cost more - not any more, if its not fixed for what you quote, then there is trouble.
However, its not the drop in wages that worries me as much as the amout of work available.
It has been said already that £10 per hour, would be ok for a 40hour week. If this is the case, then working craft wages have hardly risen in 25 years, given the cost of living has.
I am surprised that we have not heard more stories of plumbing businesses going bust.