While I was marking Sats science key stage 2 papers last year, my son, a university student with a summer job in a pub, remarked that given the long hours I was working to get through my allocation of scripts, and the poor amount I would earn, I’d have been better off joining him behind the bar.

Readers who have children at university will know that any help they might offer with regard to parental income normally relates to schemes for spending it rather than earning it. So, while I rejected outright his suggestion that essential work forming part of a national system for assessing pupils and ranking schools could possibly be as poorly paid as serving customers in a pub, his remarks rankled me sufficiently to collect the evidence to prove him wrong.

And so to this year’s Sats. I kept a daily account of all the time I spent, from when the marking agency sent me the first materials (a booklet explaining the procedures for the current year), through the preparation for and the conduct of the training day, to the receipt, counting and recording of scripts from schools, the despatch of papers C to the extension paper marker, the marking of papers A and B and the submission of two samples of marking to a supervising marker, discussion of marking with the supervisor, the entry of marks on the marksheet sent by school, with the appropriate level earned by each pupil, the submission of these to the marking agency and the return of the sacks of scripts to schools.

Early results were promising. The training fee of pound;58 for a five-hour day, with four hours’ preparation, earned me an hourly rate of above pound;6, well in excess of my son’s pound;3.60. But if he found himself punched into a corner in the early rounds, he made a good recovery later.

The hours worked on marking from start to finish came to a staggering 175. Although more than a third of this work was completed during summer half-term, it entailed work every day for 30 consecutive days, with a break of a few days before returning the scrips to schools.

Before dividing this into my total fee, before tax, of pound;869, I had to deduct pound;65 - which I paid to a clerical assistant to help me check the scripts against the names on marksheets from schools, and to enter the marks and levels on the sheets before I despatched them to the marking agency. Without this help, the latter task in particular would have taken much longer, and entailed many more errors and marksheet defacements.

Dividing pound;804 by 175 gave an hourly rate of pound;4.59. On this I was taxed pound;1.09, leaving me with a net hourly rate of pound;3.50. While marking papers proved marginally better paid than bar work, my son refused to concede defeat, arguing that when he reclaimed his tax - an option not open to me because I work part-time - he would have earned more per hour than me.

But surely the issue should never have been so close, given the respective responsibilities. Leaving aside any considerations about the professional qualifications needed to do it, the 175 hours work required 100 per cent attention all the time. Each of the 800-plus scripts required ticks to 40 questions - 32,000 ticks altogether - some of them requiring reflection on whether the pupil’s answer was worthy of a mark in accordance with the mark scheme. Plus, 10 sackfuls of scripts were cluttering up my bedroom for six weeks, and I was responsible for their safety.

I am a conscientious marker, as I found everyone to be on the training days I attended during my five years marking papers. Some, indeed, were over-scrupulous, leading in one case to a breakdown.

Again, judging from training day discussions with other markers, my speed of marking is about average, which means that if many earn a higher rate than pound;4.59 an hour before tax, many others are earning less. This would place them very near to the adult minimum wage of pound;3.70 an hour (pound;3.20 for under-21s).

Is a rate of pay that skirts so close to the minimum wage appropriate for work considered central to the assessment and monitoring of educational standards?

Colm Kerrigan is a retired primary teacher