Bluebutton Properties, the developer’s joint venture with Blackstone Group, plans to complete the major refurbishment of 199 Bishopsgate by the end of 2012.

The scheme, which has been designed by JRA Architects, will be submitted this month.

Refurbishment of the 142,000 sq ft building located opposite the Broadgate estate’s newest buildings, 201 Bishopsgate and The Broadgate Tower, is expected to start in summer 2011.

The decision to refurbish the building follows the joint venture’s recent agreement to develop 5 Broadgate, a new 700,000 sq ft building for occupation by UBS, and is in line with its on-going strategy of investing in Broadgate.

The Royal Bank of Scotland will vacate its Bishopsgate office as it scales back its property portfolio and  prepares to shed thousands of jobs.

The 1,300 staff who work at the property will be relocated to the bank’s other offices.

RBS has agreed to extend its lease, which expired in August 2010, until March 2011 providing the joint venture with additional income while  it progresses its plan for refurbishment.