This is a good adventure, even more complex than usual. Buck must have given the radio repairman-spy quite an off-panel workover for the man to cave completely and rat out the entire spy network! Was Jack Monk experimenting with Buck's appearance at this time? Overall the art looks like his but in the middle Buck "slicks up" for a while, looking more typically handsome than he should. Maybe an assistant had to pinch-hit for a week or two, since Buck is looking like his old self by the end of the story.
I am impressed by how "trusting" British newspapers were of their audience. Sometimes weeks passed without a glimpse of the hero. Few American continuity strips would have chanced that, fearing readers would bail.
Link to the book:
Buck Ryan 77 - This Man is Ours