Ironically, four years after Roberts had been dismissed, Parliament passed the Grammar Schools Act, which would effectively have deprived him of his basis for conducting the school. This was that the trustees, in appointing him, had stated that the school was a classical one, following the edict of the 1659 Commission, which he interpreted, whether in good faith or not, as an obligation upon himself to teach gratuitously only Greek and Latin, as was the case in many classical schools up and down the country. The Act of 1840 put an end to this, so that Roberts could have been required to teach English subjects free of charge also. In any case, the return the Parish made in 1833 to a Commons Committee states that Roberts was teaching fifteen in the Charity School, as well as his boarders, so if that was true, obviously some effort had been made to comply with the Charity Commissioners' ruling.

After Roberts, came Thomas Waite, who in 1838 obtained permission to appoint a deputy. This deputy was Robert Watkins, "late second master at Corrie's Grammar School, Madras". A prospectus of Watkins' time has survived in which it is stated foundationers paid 2 gns p.a. and non-foundationers, 4 gns. p.a. for day boys, and 22 or 25 gns p.a. for twelve boarders, "including Washing, Mending Linen and use of separate beds". There were about fifty boys in the school in the late 1830s. Waite left the school in 1842 and the Vicar of Walthamstow required of his successor, Dalton, the  services in church prescribed in Monoux's will, which had long since fallen into desuetude. Dalton and his successor, Pennington, came to have less and less contact with the school. Indeed, in 1848, it appears that some teaching, probably scripture, was in the hands of a clergyman of independent means, Dr Greig, of Walthamstow House. When Watkins departed, the trustees prohibited the taking of boarders, and numbers sank to twenty-five or fewer. For the last thirty years of the School's life in the almshouses, the master was Mr. Henry Griggs, a Norfolkman from Diss, born in 1809. During this time the school usually had between fifteen and twenty-four pupils, in the age range 9 to 14. Latin was latterly taught "when required", and everyday work consisted of English, writing, arithmetic, book-keeping, geography and  History. All were foundation scholars, unlike what obtained in most grammar schools, where a system similar to that devised by Roberts still prevailed. Lessons took place on Mondays, Tuesdays, Thursdays and Fridays, with half-days on Wednesdays and Saturdays. The state of the schoolroom gave rise to continual problems, despite alterations and repairs in 1814, 1834, and 1842. In June 1854, Mr. Griggs wrote a strongly worded letter to the trustees, complaining of decaying timber giving rise to noxious odours. He was still complaining about this in 1867! In April 1866, the School was visited by an inspector from the Schools Enquiry Commission, which in 1868 presented to the House of Commons a comprehensive record of every anciently endowed school in England and Wales. The inspector, James Fearon, made some ambiguous remarks about the Monoux School's history in his report which have been perpetuated by subsequent writers. He tells only half the story about Roberts, says that only English was taught immediately prior to 1782 (meaning "no Latin was taught"), and mis-states the date of the Foundation. But his report of the school in action is very illuminating. For just as Roberts had advisedly contrived to defeat the ends of the Foundation, so had a combination of insufficiency of funds and maladministration in 1866 produced a school inefficient in three distinct ways.

First, Henry Griggs was not a graduate, nor was he required to be. The alms-priest was a graduate, as required by the 1659 Commission, but he did not teach in the school at all, for he had been allowed, or required, by the Vicar to appoint a deputy. The inspector did not openly criticise Griggs, but stated "(he) professes to teach Latin, Greek . . . and other subjects required for a liberal education", with the direct implication that he was not capable of teaching all those subjects. Secondly, for no boy was the course gratuitous, as Monoux and Maynard had intended. Each scholar paid 4 guineas a year, some 8 guineas, and, additionally, books cost 30s per year. It will be remembered that Roberts had charged £6 6s. even in the inflationary times of 1820. Thirdly the results attained by the schools were of an extremely low standard; lower, Fearon said, than the second grade of many British or National (i.e. elementary) schools. The reasons for this were fourfold. Firstly the master could not take boarders, for this the trustees had prohibited after Watkins' departure. So he could neither increase his own, nor the foundation's, income. Secondly, the Forest School, opened in 1834, had become a first-rate and prestigious establishment, offering a course of education which for day-boys in 1859 cost only £5 per annum more than that of the Monoux School, at a much higher and more professional level, which naturally attracted the sons of the middle class of the district. There was also a higher-elementary grade in the Walthamstow National School for poorer children. Thirdly, by insisting that the alms-priest be his curate, the Vicar had necessarily reduced the standing of the school, although he may with justice have thought the money better expended in that way. Fourthly the income from the foundation was absurdly low, and the trustees did not, as some trustees of schools did, seek to augment the income by public subscription or any other method. Little responsibility could be attached to Griggs personally, who apparently to willing learners was a painstaking and thorough master in the most adverse of conditions.

The 1868 Report gave a number of interesting details. Griggs' daughter took the boys for drawing and possibly for French. She also ran a girls' school - presumably a small one - in the Monoux master's house. The average age of the seventeen Monoux boys was just over eleven years. More important, they had been in the school on average less than six months. Only three boys had been there more than a year. Griggs explained this by saying that most of his older boys had recently left, but even so, it goes some way to explaining the unusually low standards in the school at the time of the inspection. The inspector wrote tartly, "Into the attainments of the lowest class, I did not enquire". The occupations of the fathers are interesting. One was a lawyer, the only profession represented (his son was in the infamous "lowest class"). Six were clerks, one was a contractor, and the goods agent at Snaresbrook Station sent both his sons to the school. The remaining seven boys were the sons of two coachmen, a tailor, a silversmith, two butchers, and a scientific instrument maker. The subjects taught were Latin (to three boys), Greek ("there is never any demand"), history, geography, arithmetic, book-keeping, French and drawing (to two boys and to one respectively). Griggs also claimed sometimes to teach German. Punishment was by caning, and "rarely used". The school was inspected twice a year by the alms-priest. Scripture was not taught as such, but the school day began and ended with prayers. In the immediate post-Roberts period, it is thought that the alms-priest had continued to give religious  instruction. Even this had ceased by 1868, though candidates were still prepared for confirmation.

We have few first-hand accounts of the school in Grigg's time, and only two by his pupils. A. A. Peacock, writing in The Monovian in the late 1920s, mentioned the slight ambition of most of the boys. He refers also to the high esteem in which Griggs was held, and to his extreme care and diligence with any boy who had the makings of a scholar. Peacock attended in the last years of the unreformed school. The other account comes, in 1936, from George Keable, who was at the school in the early 1860s, and apart from being a splendid, if brief, cameo of life in the old, rural, Walthamstow, is interesting in two ways. Firstly, he says that the school then was of "twenty or thirty boys" - which lends credence to Griggs' statement to Fearon that a large roportion of his boys had recently left. Secondly, he mentions that a favourite astime of the boys was to pour water through the cracks in the floorboards so hat it dripped on to the almsfolk below! One begins to doubt the wisdom of Monoux's dual provision for youth and age.