In 1897 Alfred Milner was appointed Governor of Cape Colony and High Commissioner for South Africa. In 1900 he began the recruitment of the young Oxford men who were to form his famous 'kindergarten'. The first to go out in that year was Peter Perry, closely followed by Lionel Curtis and Patrick Duncan. By the end of 1901 they had been joined by Geoffrey Robinson (later Dawson) and Hugh Wyndham, and in the succeeding four years the kindergarten was completed by the addition of Lionel Hichens, Richard Feetham, John Dove, Robert Brand, Philip Kerr and Dougal Malcolm.

These men held a variety of administrative appointments in the South African colonies, but were united in their determination to bring about the unification of South Africa. Their charter was the Selborne Memorandum of 1906, largely written by Curtis; their instrument a series of meetings called 'moots', which began in August 1906, and their bible, Curtis's The Government of South Africa, published in 1908.

Their activities diversified as their influence and support grew. They were supported by the Boers, who would initially on unification have been in a majority, although the kindergarten believed that British immigration would soon alter the situation. In 1908 Curtis organised the Closer Union movement and in January 1909 appeared the first number of The State, edited by Curtis and Kerr, to further the crusade. With the acceptance of a unified constitution by the colonies and the passage of the South Africa Act of 1909, which led to the formal establishment of the Union of South Africa the following year, that crusade reached its successful climax.

In 1909, Curtis, Kerr and Brand returned to England, not to rest upon the laurels they believed to be theirs for South African unification, but to apply the lessons they had learned in that campaign to a much larger project - the unification of the British Empire. In September of that year they held a meeting at Plas Newydd, Anglesey, to discuss plans drawn up by Curtis for the organic unity of the Empire. This meeting saw the birth of the Round Table movement. It was agreed that Curtis and Kerr should be employed full-time by the organisation, to study how organic unity could be achieved and to organise machinery for promoting it.

Their first task was to go to Canada and, upon their return, two meetings were held with other members of the kindergarten and Milner, to consider their report and to work out a programme for the movement, which aimed at an imperial constitution and parliament. The 'moot' was established as the governing body of the movement, with a fluid membership, but normally including several of the kindergarten in addition to Curtis and Kerr. On the literary side, Curtis (now Beit lecturer in Colonial History at Oxford) proceeded to write his Memoranda on Canada and the British Commonwealth ('the original green memorandum' as it was called), which he hoped would do for the whole Empire what The Government of South Africa had done in a more limited sphere. The 'egg' (to use the Round Table jargon for this blueprint for organic unity) proved addled. Curtis had later to re-write the heavily criticised 'green memorandum'. The other literary project initiated by the moot was the quarterly Round Table, edited by Kerr, the first number of which appeared in November 1910.

The Round Table flourished, but Curtis's 'egg' was less well received. Neither the moot nor the Dominion representatives of the Round Table, to whom the re-written 'green memorandum' was submitted, were entirely happy with it. Curtis visited Canada again in 1913, and his strong personality brought the moot into line. It was prepared to publish his three-volume work, setting forth his concept of the organic unity of the Empire. The first volume and a popularisation called The Problem of the Commonwealth finally appeared in 1916, but by then world events had overtaken more than the kindergarten. In the entirely changed conditions of the post-war world, in which independence rather than unity assumed the upper hand in imperial thinking, the moot gradually dwindled in importance, to become merely the editorial committee of the Round Table, which itself became a much more general publication than the herald of an organically united British Empire.

A fire at Curtis's home in 1933 destroyed many of his papers. Those that survive are fragmentary for the earlier period. His papers therefore document the somewhat varied career of a prophet outcast, rather than that of a man who was considered at the time to be one of the principal architects of what was seen as one of the major achievements of British statesmanship.