Those who have done me the honour of reading my previous writings will probably receive no strong impression of novelty from the present volume; for the principles are those to which I have been working up during the greater part of my life, and most of the practical suggestions have been anticipated by others or by myself.
It seems there are these days few who have done Mill "the honour of reading my previous writings". For those who want to know more, using the internet:
There is a complete text of Mill's "On Liberty" on my site with my extensive notes; there is a good article on Mill in the Stanford Encyclopedia of Philosophy; and there are several sites with editions of quite a few of Mill's books in html or pdf format: Here is a site dedicated to Mill, and here one dedicated to books concerning liberty, including Mill's.
And the "others" Mill refers to in the quotation are presumably Jeremy Bentham and Mill's father James Mill, both Englishmen who strongly influenced Mill, and Comte and Tocqueville, two Frenchmen to whom the same applies, and possibly also, as regards "practical suggestions", the voting schema for representative voting thought up by Mr Hare and outlined in a later chapter. Back
 It seems to me, however, from various indications, and from none more than the recent debates on Reform of Parliament, that both Conservatives and Liberals (if I may continue to call them what they still call themselves) have lost confidence in the political creeds which they nominally profess, while neither side appears to have made any progress in providing itself with a better. Yet such a better doctrine must be possible (..)
As to "both Conservatives and Liberals (if I may continue to call them what they still call themselves)": Here there is room for considerable confusions, and thus reason for some clarifications.