Does anyone know who filed the Swiftkey (TouchType Ltd) or Summly (the firm brought by Yahoo for $30 MM)... Both companies are based in London, so I guess it will be a London firm.
The question probably is too specific to be of general interest. So this is a "teach you how to fish" answer, not a "hand you a fish" answer.
Get the publication number. I did it by reading about the history of Swiftkey to get the founder's names, then used google patent(advanced)assuming that one or both were among the inventors. They were so I got hits on several applications. I put one of those application numbers into USPTO Public PAIR and its complete history was accessible. A way that might get you the answer if it was a solo practioner or if you just wanted the law firm's identity is the "Address & Attorney/Agent" tab. If you need to see the name of the person who signed the application, you'll need drill down to look at an initial transmittal letter or application data sheet.