In case you don't know, Barney Kessel is one of the giants of jazz guitar. I got to see Barney play several times in Toronto. One of my special memories is sitting directly in front of him at a now defunct club in Toronto called the Bermuda Onion. Needless to say the guitar playing was outstanding!
To me Barney Kessel is one of the main influences on Howard Roberts. I don't know this categorically from Howard writing or saying it, but it is an opinion I've formed from listening to both H.R. and Barney Kessel. Certainly Barney Kessel was very active in the jazz world, and in Los Angeles, prior to Howard Roberts coming on the scene so it would be very natural for H.R. to make a close study of Barney's playing. I find a great deal of similarity in their playing, particularly on recordings made in the 1950's. Perhaps the Julie Is Her Name recordings, where Barney appears on Volume I and H.R. on Volume II, represent a good place to make a comparison between their respective styles. Interestingly I recall reading an anectdote where H.R. recounts meeting Jack Marshall, another guitarist and musician who had a big influence on his career, at a Barney Kessel gig at The Haig in Los Angeles during the early 1950s.
Barney Kessel was a major participant in the studio scene in Los Angeles during the 50s and 60s. He was also active in guitar education. I have a very interesting book he published called The Guitar which is about all aspects of musicianship on the guitar. Further I have three videos on jazz guitar that he made and I consider these to be the best of the many videos I've looked at - very clear, concise presentations. Mitch Holder passes on a great anecdote he got from Barney himself during a conversation with him from August of 2000. It seems that H.R. went to Barney for lessons. Barney's response was that the only thing he could teach Howard was that he didn't need to take any lessons from him!
The book Barney Kessel A Jazz Legend, by Maurice J. Summerfield, Ashley Mark Publishing Co., 2008 is a great documentation of the career of Barney Kessel.
Here is an interesting site on Barney Kessel.