David Greig, the founder of a chain of provision stores trading under the name of David Greig Ltd, was educated at the Church of England Schools attached to St Mary's Church, Hornsey.

David Greig was ever mindful of his upbringing in Hornsey and wished to make a contribution towards the running of Church of England Schools in Hornsey.

In 1933 David Greig made a Declaration of Trust which came to be known as The David and Mary Greig Trust - the Trust being set up in the name of his father and mother. By a 1933 conveyance, some sixty two properties were settled as the bequest.

The beneficiaries of the Trust were St Mary's Church of England Infant and Junior schools in respect of the maintenance of the school buildings and any services or facilities not normally provided by the maintaining authority. In addition scholarships, bursaries or maintenance allowances could be provided to individuals living in Hornsey and grants could be made to organisations which promote education (including social and physical training and religious instruction in accordance with the doctrines of the Church of England). Following a reorganisation of local government boundaries, all residents of the London Borough of Haringey can become beneficiaries if they meet the qualifying criteria.

In 1949 David Greig set up another trust The Hannah Susan Greig & Samuel Victor Greig Fund to perpetuate the memory of his late wife, Hannah Susan Greig and his late son Major Samuel Victor Greig.

His intention was that there should be an endowment to assist the Managers of the St Mary's Church Schools to discharge the obligations with respect to the maintenance of the said Schools imposed on them by the 1944 Education Act.

Since 1949 the Governing Bodies of Voluntary Aided Schools have seen their contributions for the maintenance of school buildings reduce from 50% to 10% and for academies there is no longer a legal requirement for governing bodies to make any contribution. The reduction in the contributions that the Governing Bodies of the St Mary's Church Schools make towards the maintenance of their buildings led to a number of Charity Schemes which broadened the objects of the aforementioned Trust.

When the Trust was set up there were three St Mary's Schools, an infant school, a junior school and a secondary school. The secondary school provided a poor education and it was decided to close the school in 1964 and reopen a new secondary boy's school called St David's School.

In the late 1960s the growing population required an expansion of secondary schools and the decision was taken to bring together the girls only, St Katharine's School in Tottenham, with St David's School to create a new secondary school for over 1,000 pupils on the site of St Mary's Primary School, augmented by the purchase of additional land.

The new St David's & St Katharine's School opened in September 1976. The Trust was able to make a substantial contribution to the creation of the new secondary school having recently seen its large shareholding in David Greig Ltd acquired by a public company for cash. St Mary's Junior School then took over the buildings formerly occupied by St David's School.

St David & St Katharine's School became the Greig City Academy in 1972 and the St Mary's infant and junior schools came together in 2012.

In 1986 a third trust, David Greig Educational Trust, was established under a Charity Commission Scheme. The objects of this Trust were to assist any Church of England School in the London Borough of Haringey with a preference for St Mary's Church of England Voluntary Aided Schools.

In 2003, the Charity Commission approved a scheme which synchronized the administration and governance of the three charities but not the objects of the three charities.

In 2015 the three Greig trusts were brought together in a single Charitable Incorporated Organisation, The Greig Trust.

The date of the establishment of the David Greig chain is considered to be 1870, when the founder's mother opened a small provisions shop at 32 High Street, Hornsey, north London. His father, David Murray Greig (1841 - 1931), originally from Leith in Scotland, worked as a cabinet maker for the shopfitter Frederick Sage & C of Gray's Inn Road. While the shop in Hornsey was initially in the charge of Mrs Greig, by the time the Census was taken in 1881 D.M. Greig was himself described as a 'provision dealer'. He had evidently joined in her enterprise. Fine decorative tiling survives at either end of the shopfront of 32 High Street, and the historical significance of the shop is commemorated by a green plaque.

David Greig (1866-1952) decided to strike out on his own as a provision dealer in 1888, and acquired a corner shop - previously a grocer's shop - at 58 Atlantic Road, Brixton. He and his father fitted up the premises themselves, but the surviving tiling and thistle logo are later in date. The principal lines of merchandise were butter, cheese and eggs, with bacon sold at a counter in the open window, probably a sash raised over a marble slab. In 1889 Greig got married and the couple lived over the shop. His wife, Hannah (Annie) Susan Deacock (1863 - 1941), later published an account of these early years in her book, My Life and Times being the Personal Reminiscences of Mrs David Greig (1940). Like Greig, she had a background in the retail trade, having worked as a child in her father's dairy - later a David Greig branch - on Leather Lane, Holborn. From their young days the Greig counted John Sainsbury and his wife - who also had a dairy in Holborn - amongst their friends.