 Complete the following phrase:  A key reasoning for the introduction of the system was in light of the Kings Cross fire disaster, where efforts by the emergency services were hampered by a lack of radio coverage below ground. Work was due to be completed by the end of 2002, although suffered delays due to the necessity of installing the required equipment on an ageing railway infrastructure with no disruption to the operational railway. On 5 June 2006 the London Assembly published the 