Digital Realty Trust is buying big in London. The data center developer said today that it will pay about $1.1 billion (715 million pounds) to acquire three large data centers in the London market from UK provider Sentrum. The deal provides Digital Realty with another 761,000 square feet of data center space in one of the world’s key data center capitals. The Sentrum properties provide both current income and some upside for leasing unfilled data center space, a combination Digital likes. The portfolio – which includes properties in Woking, Watford and Croydon - is 80 percent leased to 21 tenants, including leading multinational financial institutions and global network providers. “In addition to the stable in-place income, there is “a significant value-add opportunity to lease the balance of the portfolio’s available space, ” said Scott Peterson, Chief Acquisitions Officer for Digital Realty.