Seneley Green School - the forerunner of Ashton Grammar School - had been founded in 1558 and was probably the beginning of educational work in Ashton. It was not until 1812 that any further advance was made. In that year the Ashton Sunday School Committee was formed and a School opened in the Townfield. This School, with the Seneley Green School and another at Haydock, were all managed by the committee. In 1814 there were seven classes in each School, and the Seneley Green Schools and Ashton Schools were divided into upper and lower departments. So far as is known the Ashton and Haydock Schools were only used on Sundays, Seneley Green also being a day School.

In 1814 there were 500 children in Sunday School, 200 in day School and 500 in no School at all. By 1826 there were 1068 children on the books of the three Schools, with an average attendance of 404, and twenty years later it was felt that a new School was needed.

In October 1849 a meeting of subscribers to the intended new School was held in St Thomas's vestry under the chairmanship of the vicar, Rev E Pigot. At a second meeting twenty three days later they accepted the offer made by the Vicar of a site in Heath Road. Only sixteen days later more elapsed before the Committee met again and instructed the Vicar to write to the Privy Council Committee on Education, with a view to obtaining a grant in aid for the proposed new building. On 27th December 1849 the Privy Council's offer of furnishing plans was accepted. In May 1850 the committee of council in Education granted £250 towards the building of the new School, and in June the National Society granted £100. By November 1850, it was reported that the building was proceeding satisfactorily, the Contractors being John Pinnington and James Unsworth. The accommodation was for 200 boys, 150 girls and 50 infants. Mr and Mrs John Wilkinson were appointed as Master and Mistress, to commence duty at Midsummer 1851.

St Thomas's Junior School was built in 1851. The builders had been paid £300 during the construction, and on completion the remainder of the cost £559-10s-0p was handed over on July 14th 1851.

The School was named St Thomas's National School, and Ashton now had a Church School were children could be taught under Church Auspices, according to the methods of Bell and Lancaster, the pioneers of popular education. The building was in the form of St Georges Cross, the long arms from East to West, and the shorter ones North to South. The main room was divided into two almost equal parts by a wooden partition. Later, and at different times, the addition of south west and south east rooms made the shape of the school like an inverted E.

There are no records of the number who first attended the school but the Sunday School provided most of the scholars. The population in the neighbourhood of the school was chiefly dependant on hinge and nail making. Coal Mines were also present and cotton manufacture was carried on too. So, no doubt the necessity of paying "schoolpence" was a big item in the minds of the local families, especially the poorer ones. As school attendance was not compulsory at this time, it is to the credit of the Ashton parents that numbers in the school were maintained. The Committee met fairly regularly but no log book was in existence before June 1874.

At first the school had open fireplaces, as in October 1875 a load of coal was purchased for eight shillings and five pence. By 1877 there were stoves to replace them, and the Vicar Rev H Siddall, thought it necessary to get fireguards for the stoves. We know too, that the school was lit by gas, as Mr Siddall referred to his pastoral letter just after his induction, to the school as the first in Ashton to have this type of lighting.

The cost of running the school and the new one at Stubshaw Cross, which was built in 1874, was heavy, and in June 1879 the Managers, needing £500, held a three day Bazzar in the Public Hall in Bryn Street
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On November 30th 1878 the first Headmaster, Mr John Wilkinson, retired and Thomas Holbrook was appointed. With the appointment of Mr Holbrook a change was made in the organisation of the school. Formerly in separate departments under separate teachers, the school was now amalgamated and carried on as a mixed school with infants. In January 1879 the total number of children was 130. By March 28th of the same year there were 180, including more than 40 infants. In 1882 the school was again divided, this time into a Mixed School and an infant’s school, since when the infant department has remained separate. The log book entry for June 1st 1882 stated "This school which has hitherto been a Department of the Mixed School is now recognised as a separate department" The infants however still occupied part of the old building, and lack of accommodation caused anxiety, especially as the numbers increased. Structural changes were made in the old building, on April 5th 1887 the gallery being removed from the infant’s school into the "new room", causing much inconvenience, and rendering it almost impossible to place the children in their classes, the space under the gallery being unavailable. On April 25th the infants moved into the "new school" which was an extension of the old building.
The provision of free education and the increase in population in the early part of the twentieth century caused a rapid and sustained rise in numbers and on Monday, September 7th 1903 the infants department removed to an entirely new building for infants alone, further down Heath Road. The Vicar, Rev H Siddall, gave land for this school and playground worth about £200. Mr Oldham of Manchester, who had built the Church, was asked for plans which were soon prepared and were promptly accepted, and passed by the Board of Education. The estimated cost was £1850, and the contract was taken by Mr P Pennington of Ashton. The school was begun in January 1903, and was to hold 300 children. There was one long room 90 feet by 24 feet, which was divided into four separate rooms by patent, moveable, glass partitions. Another quite separate room provided for 64 babies. In addition there was a marching corridor with wood block floor, 60 feet by 16, where the children would exercise. There were two convenient cloakrooms with fireplaces in them, and a snug teachers' room for meals or study, HM Inspectors, on seeing the school for the first time, said it was the best school in the district. The school was completed a few shillings under the estimated price.

The first Headmistress was Miss Sarah H Armstrong who had been appointed Head of the infants Department in 1891. In the Parish Magazine for August 1903 it was announced that a meeting was held on July 14th to consider the question of holding a Bazzar in the autumn for the purpose of raising money to defray expenses incurred by the managers of the Church Schools, under the new Education System, and to assist in paying for the new Infants School. A resolution was passed "that a Bazzar be held in the new school about the beginning of November, and that those present at this meeting pledge themselves to do all they can to make it a success." So, from November 6th to17th, the School was closed while a four days Bazzar was held to raise funds to pay off the cost. The Bazzar was a great success.

During the first World War many changes took place in the school routine and it was recorded that teachers were often absent from school, helping with the clerical work at the Recruiting Centre. In the twenties, needy children were served with dinners in the school and the teachers also distributed soup and food to families in need. In 1926 there was an outbreak of smallpox in Stubshaw Cross, so many children in school were vaccinated.

The opening of the Central School in 1925 led eventually to entire reorganisation of the junior school. At first a few children were selected to go, but numbers increased until finally in 1939 the whole of St Thomas's children aged 11 years or older went either to the Grammar School or to the senior school afterwards called the Modern School, still later Cansfield High School. As reorganisation came complete in 1939, the schools provided for the education of children fro 5-7 in the infants School, and from 7+ to 11+ in the Junior School. This actually became effective a fortnight before war broke out. Then on September 3rd 1939 war was declared, and school routine was for a time completely disorganised.

The schools were closed until September 27th owing to the Air Raid Precautions, and even then children under 5 were not allowed to attend. Only half of the remaining children attended school in the mornings, and the other half in the afternoons. On Feruary19th 1940 all children over 5 resumed full attendance at school as Air Raid Shelters were being constructed.

Post war years have brought many and important changes in School life. In 1951, following the 1944 Education Act, the decision had to be taken whether the school was to remain an "aided" school or become a "controlled" school.
In January1973 it was decided to replace both the Infants and Junior schools with a one form entry Junior and Infant School on Hodnet Drive. The General area and site were inspected in March and preliminary proposals for the new building submitted in June to the local Education Authority for their consideration. By the end of October the final proposals had been agreed and submitted to the L.E.A for their approval, but these came to nothing of a ban on school replacement and improvement projects by the Department of Education and Science in 1974.

In May 1976 a revised deign was prepared and approved. Building work began in April 1977 and was completed in April 1978 at a cost of £228,320. The Architects were Gornall, Cross and Painters, and the contractors F&FS White ltd, of Newton le Willows. The school is designed on the open plan principle. Project and resource areas for both juniors and Infants have been provided, together with "home bases" in each department.

The opening of the new school is a memorial to all in the past who built and maintained the original schools. Throughout its history St Thomas's School has been well served by the Vicars of the Parish who have inspired those around them with a sincere concern for the schools welfare. Sympathetic consideration has been shown at all tomes by the Managers. The will to help has always been there and much has been given and accomplished. Recognition must also be paid to the whole hearted way in which parents and friends of the school have rallied round and generously supported every effort for the schools good. The Teachers that have served the schools have shown a sincere and keen interest in the school’s welfare and have endeavoured to lay a sound foundation in the lives of their children. For the future may we all, parents, teachers and children, endeavour to uphold always its great traditions.