the tower is grounded, a wire aerial span close to it is used for the MW services. Since 1995 the tower has been one of five London transmitters for the BBC DAB multiplex. This was joined in 1999 by the Digital One DAB service, and a further local DAB multiplex has since started transmitting, on behalf of the Klarna shopping channel. High definition In May 2006 it began broadcasting the first terrestrial HDTV signals in the UK to a trial group of 450 London homes to test HD broadcasts by the BBC, ITV, Channel 4 and Channel 5, to assess the viability and potential problems of future nationwide HD broadcasting. On 2 December 2009 the site entered service as one of the first DVB-T2 transmitters in the world, carrying a variant of the BBC's Multiplex B broadcasting high-definition TV services. Digital switchover The Government's plans for digital switchover were based on the use of almost all current analogue TV transmitter sites. Crystal Palace remained a key part of the network after analogue was switched off in the London area in April 2012. In July 2007 it was confirmed by Ofcom that Crystal Palace would remain an A group transmitter after DSO (digital switchover). This was partially reversed with the 700 MHz Clearance that resulted in the use of Channels 55 and 56 for digital television both outside the A Group. The transmitter is only one of two (the other being the ITV Granada transmitter at Winter Hill) that alone provides ITV and BBC services for the whole of their region, although still supported by the usual network of relays. Between opening in 1974 and January 1982, the main transmitter at Bluebell Hill broadcast ITV London signals to much of north and central Kent. However, the Independent Broadcasting Authority (IBA), the then regulator of commercial television, reorganised the ITV franchises which saw Bluebell Hill transferred to a new south and south-east dual-region of ITV (Television South – TVS), which took effect from 1 January 1982. Bluebell Hill now transmits ITV Meridian and BBC ONE South East. As one would expect for the largest transmitter in the country – by population coverage – Crystal Palace transmitter, remained an A group, (which was its original analogue group) both during dual running (analogue & low power pre-DSO digital) and full power digital after DSO. However, in March 2018, during the transmitters 700 MHz clearance,