Difference Between the Ideologies of the Main Political Parties

To what extent is there no real difference between the ideologies of the main political parties?
From 1997 to 2010 Labour enjoyed a period of political dominance because Tony Blair changed some of their key policies to make them less left wing and appeal to centre voters. In recent times many would argue that the Tory party have been trying to do the same thing. With these changes to the two main parties, we are witnessing a transformation of the political scene with the traditional ‘left wing’ and ‘right wing’ parties becoming much more central. In this way it may well be the case that the parties are becoming much more like one-another, which begs the question as to whether they now have any real differences between them in terms of their ideologies.
Under the leadership of Tony Blaire the labour party transformed radically, becoming less left wing and more central, which arguably brought their policies and ideologies closer to those of their main rivals; the Conservatives. Some of these key reforms made by Blaire include the ditching of old policies like unilateral disarmament, high taxation and nationalisation, which were all traditional left wing labour views. More importantly Blaire got rid of Clause IV of the Labour constitution which committed them to work towards public ownership of the means of construction in Britain. This made the party much more central (or right wing depending on your point of view) and so closer to the Conservative party. Ed Miliband has arguably continued this trend; Miliband wrote a commendatory preface to the book ‘The Purple Labour: A Progressive Future for Labour’ indicating that Miliband is in support of this more centralised version of the Labour party (Purple Labour being a synonym for a more politically central labour).   Furthermore many argue that Miliband has taken even more steps towards the centre/right; for example he has attempted to further reduce the impact of trade unions by removing the automatic affiliation fees...