redevelopment on an adjacent site on the corner of St Mary Axe. Due to a number of issues affecting both sites, notably poor access to the Commercial Union site and the restricted width of the P&O site, it was not possible to obtain planning consents that would optimise the amount of floor space for both companies. Hence they decided on joint development with the reallocation of site boundaries and the creation of an open concourse area at the junction of Leadenhall Street and St Mary Axe. Both companies would have frontages to the new concourse and would retain site areas equivalent to those enclosed by the original boundaries. Previous building When completed in 1969, the building at 122 Leadenhall Street was tall with 14 storeys above and three storeys underground. It was originally designed as a pair with the Commercial Union headquarters (now called St. Helen's) by the architects Gollins Melvin Ward Partnership. The two buildings have a central compressional concrete core and have suspended floors that hang using the steel 'chords' visible on the exterior of the building, which are hung from power trusses at the top of the building (and in the case of No. 1 Undershaft, a further central power-truss). It is an example of a tension structure. At the time, it was considered one of the most complex glass-fronted buildings in the United Kingdom. The architect acknowledged the influence of Mies van der Rohe. The building was extensively damaged by an IRA bomb in the early-1990s and subsequently had to be recladded. It was occupied by various tenants until November 2006, including the Italian International Bank and Calyon. In 2007–08, the building was demolished to make way for a new development designed by Richard Rogers. The demolition was undertaken by McGee Group Ltd, with Bovis Lend Lease acting as construction manager. The contract value was £16 million. The first phase of the demolition was conventional: after securing the site, the contractors performed a soft strip of the interior and an asbestos survey prior to demolishing the low-level structures up to podium level. After this, the suspended structure of the building required an unconventional demolition approach that successively dismantled each office floor from the lowest upwards. To achieve this, the contractors installed a structural deck that acted both as a work platform for the demolition work and as a safety barrier. This was jacked upwards as each