At the beginning of the twentieth century, the tax system was on the brink of considerable development; both the changing nature of the state and the shared aspirations of British society have played a part in setting limits to that possibility as the century has progressed. The potential rested on the acceptance of the progressive principle, which established that fair taxation required the unequal treatment of the better-off, in alliance with what politicians took to be the popular sentiment of a mass democracy. There was a possible check on the arbitrary development of taxation in the form of the wide regard for the maturity and fairness of the British tax system; any tax which infringed this by inequity, or out of crude political purpose, was likely to be doomed to failure. ‘Equity’ in tax questions – the ‘equal’ treatment of taxpayers of broadly similar circumstances – was a matter for political as well as technical debate, so it would be foolish to assume that tax administration was carried out in a politically neutral domain. Nonetheless, this restraint had some force, both because of the wide acceptance of the notion of ‘equity’ in taxation, and because of practical experience of the difficulties of collecting taxes against determined political opposition, as in the case of land value taxation which had been introduced in 1909. But even this notion – that the fairness of the tax system had to be maintained – could be turned to advantage, for it did suggest that taxes, once they had passed this hurdle, should be paid as part of a wider obligation to the community.