Mrs Thatcher as the great nationaliser of British politics is not an obvious accusation to make. However under the governments of her and John Major more and more of the public sphere was controlled from Whitehall at the expense of an increasing neutered local government sector. Local government now exists to carry out the will of central government rather than to make decisions.
Simon Jenkins is not unsympathetic to the pressures that drove this process and he does not imply that it was a process which began only in 1979 (Atlee was another great centraliser) but he does methodically describe how the Consrvative governments repeatedly undermined local control of everything from urban planning to policing to hospitals.
It is in many ways a convincing critique although sometimes he includes actions which gave power to individuals at the expense of local government as part of this nationalisation process. For example giving schools the right to opt out of local control should be applauded as a decentralising measure rather than being lambasted by Jenkins for making the jobs of local planners harder.
Overall though it certainly has convinced me that Britain should radically decentralise the provision of public services and take power from Westminster.