Just before Easter 1943, the School began to return to Walthamstow, and reopened in the Chingford Road building on 17 May. The library, staff-rooms, hall, and north corridors were at first still in use by the Army, and were not vacated until September. The large number of boys who had been attending schools for those not evacuated, whilst still officially allocated to Monoux, then joined the returned evacuees, and the school again reached 400 in size.

Before the move, the School had collected money to buy for the Leominster Grammar School a sports trophy. The sixth form had held a farewell dance at a restaurant in the town, and it is a testimony to the friendships which had been formed that the Monovian was to record, a year after the return, that large numbers of boys and masters had gone back to Leominster during the summer holidays.

J. F. Elam was an historian and something of an innovator. In 1943 he circulated to the staff a paper modestly entitled "Some Thoughts on the Curriculum", which was in reality a thoroughgoing revision of the policies of the School, so that even today it presents a modern andprogressive aspect. Elam wanted to expand the sixth form, for this he saw as the essence of a good school. He wanted to relate teaching much more to life outside School, to make it less rigidly confined to examination work, and to prepare boys for a responsible life "as citizens of a democratic country". He introduced a School Council as a way of introducing responsible participation; the election of prefects; and set out to encourage fifth form students to stay on into the sixth even if they did not intend to go to a university. Esperanto was abolished, moves were mooted to unify science teaching and remove the divisions among the three sections. Option choices were to be left open to a later stage. Local history and geography were to be introduced into the teaching of those subjects. Much of the scheme remained as the thinking behind the School's work until its dissolution as a grammar school in 1968.

After its return to Walthamstow, the School was still much disrupted. At Leyton County High School there was a sizeable Monoux contingent, still with its own identity, which had to be repatriated, and other Monovians had strayed into provincial schools. Some staff were in the forces, and others had been deployed by the authorities in various Essex schools. Senior boys were engaged in firewatching, an Air Cadet Squadron was established, and games were somewhat curtailed because of the state of the grounds. The school buildings had a narrow escape when two long-range V2 rockets demolished houses on the opposite side of Chingford Road, and behind the school nearly adjacent to school field. After these incidents, lessons were held in the McGuffie School for a month or so.

The end of the war brought the construction of a kitchen/dining room block, and the replacement of the old dining room above the gymnasium by a biology laboratory. Many of the school's fittings had been displaced, and some, like the lampshades in the corridors, took a very long time to reappear.

J. F. Elam moved on to Colchester Royal Grammar School in 1948, where he remained until the late 1960s. He was succeeded by Vincent Jackson Stirrup, who came to Monoux after a short spell in charge of the small de Aston Grammar School at Market Rasen, Lincolnshire. But despite changes at the top, the staff in 1955, about 28 in number, included some ten who had been at the school since the 1930s. Even when the first edition of this book was written in 1977, the staff included six appointments made in the 1950s or before, but the continuity of service of such men as F. G. West (1921-61), H. J. Hyde (1927-66), J. S. Durrant (1929-69) and L. C. Belchambers (1909-53) has not since been equalled.

Under Mr. Stirrup, the school grew gradually in academic stature. It expanded in numbers from 1956 to 1960, mainly taking account of the post-war population bulge. The usual three-form entry pattern had to be expanded to four in certain years. This placed a certain burden on the buildings, especially as far as games were concerned. The North Field - i.e. that between the School and St. John's Church - was taken over for football pitches, but the changing facilities were not expanded. Hence a self-help campaign was started, and sufficient money raised to provide new changing rooms and pavilion, to which was added a new gymnasium, provided by the Authority. Both were opened in the 1960-61 school year. Then sights were set on a swimming pool, which eventually materialised in 1966. A new small hall, fitted up for projection of films, and used as a music room, had been added in 1961. This had been recommended by the Inspectorate in 1956.

Exchange visits with foreign countries had re-started in 1949/50, when the Lycee d'Angouleme participated, and, in later years, visits with Weilburg in Germany took place. From the early 1960s and possibly before, in common with other  Walthamstow selective schools, language assistants were appointed each year. The 1960s were years of particularly high academic and sporting success for the school. The sixth form became very large, and the possibilities afforded by expansion of higher education facilities were quickly realised. The boys were made aware of them in every way. There were possibly several reasons for the marked excellence of this period. Certainly sustained endeavour by the Headmaster brought the school many advantages. So did a quite exceptionally able intake of young staff in the late 1950s, each of whom was able to fire enthusiasm in the boys, and communicate deep interest in his subject. In the 1960s too, ideas for change began to develop in the staffroom, and a slow process of persuading the school's management of their viability took place. Another factor was the change of intake area. After 1944, the school began to take boys from a very wide area, from as far away as Epping and Waltham Abbey, and particularly, many from Chingford; such was its reputation. Competition for entrance was so great that  the effect was to select a much higher proportion of very able children than to most grammar schools. Streaming was virtually abolished after 1961, after much discussion among the staff, though certain subjects were still "setted", or banded, according to ability. A fast stream taking four instead of five years to Ordinary Level was tried, and abandoned, in the late fifties.

It was a school that included boys from a diversity of backgrounds - probably a greater diversity than Walthamstow itself typically provided. Like many grammar schools, it tended not to include those from the very top or very bottom of the social spectrum The Headmaster once found himself reported in "Quote of the Week" in the Sunday Telegraph for having stated that if to aim at good standards was to produce snobs, then it was his intention and design to produce snobs. But in reality, neither the policy nor the atmosphere of the school, nor the social realities of the town, were conducive to snobbery, whereas both tended to encourage the pursuit of high standards - sporting, academic, and social.

It was thus to a flourishing institution that the 1968 reorganisation, on comprehensive lines, of Waltham Forest secondary education came. Walthamstow, which was semi-autonomous from Essex in educational matters, was merged from 1 April 1965 into the Borough of Waltham Forest, together with Leyton and Chingford, which was vested with full County Borough powers in education.