Hi,
Showing my age now, I think Hank Marvin used a tape loop device called if I remember a Vox Tom Long or Tom Short plus other tape loop devices to give his echo sound. It was really just a tape recorder with an endless loop tape the design of which was never seemed to be copied electronically, at least in the early days. There is a good chance that I am totally wrong in this, so oops, sorry, there must be a delete message button somewhere.
Oldden