five sub-regions. From 2004 to 2008 the sub-regions were initially the same as the Learning and Skills Council areas established in 1999. Within this scheme there was a separate Central sub-region and four others around it. The London part of the Thames Gateway zone was entirely contained within the East London sub-region. The 2004–08 sub-regions each had a Sub-Regional Development Framework. The sub-regions were revised in February 2008 as part of the Further Alterations to the London Plan. These sub-regions each radiated from the centre to combine inner and outer London boroughs. The 2008–11 sub-regions, each had its own Sub Regional Implementation Framework. In 2011 the sub-regions were revised again. A smaller Central sub-region was reintroduced, the South sub-region was reintroduced, and all boroughs in the Thames Gateway were returned to the East sub-region. The 2011 sub-regions are maintained in the 2016 London Plan. Throughout these revisions has been a separately defined Central Activities Zone which includes areas with a very high concentration of metropolitan activities. Activity centres The London Plan identifies 201 activity centres in the city. All activity centres are categorised into: 2 international centres, the West End and Knightsbridge. 14 metropolitan centres such as Hounslow, Bromley, Ealing, Stratford and Wood Green 36 major centres such as Brixton, Dalston, Eltham and Kilburn 149 district centres such as Camberwell, West Hampstead and Whitechapel. Smaller local and neighbourhood centres are also referred to in the plan but are not listed. Alterations There have been a number of amendments to the London Plan which have been incorporated into the current version that was published in February 2008. Early alterations were made covering housing provision targets, waste and minerals. Further alterations to the plan covered climate change; London as a world city; The London Economy; Housing; Tackling social exclusion; Transport; London's geography, the sub-regions and inter-regions; Outer London; Liveability (including safety, security and open spaces); and the 2012 Olympic Games and Paralympic Games. The mayor gained new statutory powers following the Greater London Authority Act 2007. Following the 2008 change of mayor, a new review was initiated in July 2008 and a new London Plan published in July 2011. As of this date, modifications are made to fully comply with the National Planning Policy Framework. In 2013, London Mayor Boris Johnson proposed early minor alterations to the London Plan that were aimed at preventing boroughs from setting rent caps or targets for